DB1BI 


VB 

AKINC 


PU  BLOW 


"The  Science  and  Practice  of 

Cheese-Making 


A  Treatise  on  the  Manufacture  of  Amer 
ican  Cheddar  Cheese  and  other  varieties 

intended  as  a  text-book  for  the  use  of    dairy  teachers  and 

students  in  classroom  and  workroom  ;    prepared  also 

as  a  handbook  and  work  of  reference  for  the 

daily   use  of   practical   cheese-makers 

in  cheese-factory  operations 


By 
Lucius  L.  Van  Slyke,  Ph.D. 


Chemist  of  the  New  York  Agricultural 
Experiment   Station 

and 


Charles  A.  Publow,  A.B.,  M.D.,  C.M, 

Associate  Professor  of  Dairy  Industry  in  the  New  York  State 
College  of  Agriculture  at  Cornell  University 


Illustrated, 


New     York 

Orange     Judd     Company 
1910 


Copyright,  1909 

ORANGE  JUDD  COMPANY 

NEW  YORK 


All  Rights  Reserved. 


[Printed  in  U.  S.  A.] 


PREFACE 

This  book  has  been  prepared  to  supply  a  need 
definitely  expressed  by  dairy  teachers,  dairy  stu- 
dents and  cheese-makers.  To  meet  the  require- 
ments of  to-day,  a  book  on  cheese-making  must  be 
something  more  than  a  mere  description,  in  a 
recipe-like  form,  of  certain  operations  to  be  per- 
formed; it  must  also  make  prominent  the  reasons 
for  each  step  in  every  operation  and  present  as 
clearly  as  possible  the  facts  and  principles  under- 
lying the  methods ;  in  other  words,  it  must  present 
the  science  as  well  as  the  practice  of  cheese-making. 

Knowledge  of  cheese-making,  as  of  any  art,  is 
two-sided,  practical  and  scientific.  Practical  knowl- 
edge tells  us  what  to  do;  scientific  knowledge  gives 
us  the  reasons  for  what  is  done.  Practice  consists  in 
doing  things ;  science,  in  knowing  things.  Knowledge, 
to  be  complete,  must  be  both  practical  and  scientific; 
we  must  know  not  only  what  particular  things  to  do 
but  why  we  do  them.  Just  in  proportion  as  the  prac- 
tical and  the  scientific  sides  of  knowledge  advance 
together,  does  the  practice  become  more  nearly  per- 
fect. The  more  one  knows,  the  more  and  better  can 
one  do. 

The  practice  of  cheese-making  embraces  a  systematic 
series  of  mechanical  operations,  which  have  been 
gradually  developed  by  experience  and  observation. 
In  its  widest  application,  it  includes  (i)  the  produc- 
tion and  care  of  milk;  (2)  the  conversion  of  milk 
into  cheese;  and  (3)  the  care  of  the  manufactured 
product  until  it  is  ready  to  be  used  as  food. 

v 

250810 


VI  PREFACE 

The  science  of  cheese-making  embraces  a  collection 
of  the  underlying  facts  and  principles  relating  to 
the  practice,  arranged  in  systematic  form  so  as 
to  show  their  relations.  For  example,  it  includes, 
among  other  lines:  (i)  A  knowledge  of  the  con- 
stituents of  milk — what  each  has  to  do  in  the  mak- 
ing of  cheese  and  how  each  is  related  to  the  yield, 
composition  and  quality  of  the  product;  (2)  the 
changes  which  each  constituent  of  milk  may  under- 
go and  the  effect  of  such  changes  upon  the  yield, 
composition  and  quality  of  cheese;  (3)  the  action  of 
micro-organisms  upon  the  constituents  of  milk  and 
of  cheese;  (4)  the  effect  of  unorganized  ferments 
upon  milk  and  cheese;  (5)  the  effect  of  temperature, 
humidity  and  other  conditions  upon  the  chemical 
changes  that  take  place  during  the  operations  of 
cheese-ripening. 

While  cheese  has  been  made  for  thousands  of 
years,  the  growth  of  accurate,  systematic  knowledge 
regarding  its  inner  details  has  been  extremely  slow ; 
but  within  the  past  twenty  years  there  has  been  an 
era  of  unprecedented  activity  in  the  investigation  of 
the  chemical,  biological  and  other  problems  con- 
nected with  milk  and  cheese.  As  the  result  of  the 
application  of  new  knowledge  thus  gained,  the  prac- 
tice of  cheese-making  has  undergone  marked  im- 
provements. The  problems  that  are  peculiar  to  the 
manufacture  of  American  cheddar  cheese  have  been 
studied  extensively  in  the  United  States  and  Can- 
ada, mainly  under  government  direction  in  some 
form,  and  more  especially  at  agricultural  experi- 
ment stations.  Two  institutions  have  been  promi- 
nent for  the  extent  and  thoroughness  of  their 


PREFACE  Vll 

investigations  and  for  the  far-reaching  influence  of 
the  results  of  their  work — the  agricultural  experi- 
ment stations  of  the  states  of  Wisconsin  and 
of  New  York  (Geneva).  The  results  of  these  and  of 
other  useful  investigations  are  not  now  easily  avail- 
able, being  scattered  through  many  reports  and 
bulletins,  most  of  which  can  be  found  only  in  large 
libraries.  One  of  the  tasks  proposed  at  the  outset 
in  the  preparation  of  this  book  was  to  digest  this 
large  mass  of  valuable  material  and  present  the 
results  in  systematic  form,  thus  making  it  for  the 
first  time  readily  available  to  all  dairy  students.  An 
exhaustive,  detailed  history  of  these  investigations 
would  compel  one  to  present  some  results  and  in- 
terpretations which  more  accurate  work  has  later 
shown  to  be  erroneous.  Those  for  whose  use  this 
book  A  has  been  prepared  are  more  interested  in 
knowing  what  the  status  of  our  present  knowledge 
is  than  in  studying  the  various  details  which  have 
preceded.  The  chief  aim,  therefore,  has  been  to 
digest  and  summarize  the  results  of  investigation 
in  such  a  way  as  to  give  what,  in  the  light  of  our 
present  knowledge,  we  may  now  regard  as  the 
probable  facts  and  their  proper  interpretation.  This 
task  is  a  somewhat  discouraging  one,  because  new 
facts  are  being  rapidly  added  to  our  knowledge 
and,  in  consequence,  what  we  may  now  hold  as 
true  is  quite  likely  to  need  modification  in  the  near 
future. 

The  main  portion  of  this  book  is  devoted  to 
cheddar  cheese  for  the  obvious  reason  that  this  is 
the  kind  most  extensively  made  in  America.  A 
few  other  kinds  of  cheese  are  briefly  discussed,  so 


Vlll  PREFACE 

far  as  the  assigned  limits  permit.  Even  in  relation 
to  cheddar  cheese,  the  book  is  not  intended  as  an 
encyclopedia,  but  an  effort  has  been  made  to  have 
it  reasonably  complete. 

The  language  used  by  the  practical  cheese-maker 
in  describing  the  operations  of  cheese-making  has 
inevitably  expressed  his  theories  or  explanations 
of  observed  facts.  Many  expressions  have  persisted 
even  after  they  were  known  not  to  be  in  accordance 
with  facts.  It  has  seemed  highly  desirable  that 
such  inaccuracies  should  be  corrected  and  the  lan- 
guage made  to  correspond  with  our  advanced 
knowledge.  In  addition,  there  have  been  many  in- 
accurate and  loose  expressions  in  common  use 
which  have  come  simply  from  carelessness  and  lack 
of  precision.  Such  expressions  have  been  carefully 
revised  in  the  preparation  of  this  book. 

A  few  words  in  regard  to  the  general  plan  of  the 
book  will  not  be  out  of  place  here.  The  subject 
matter  is  divided  into  five  parts.  The  first  part  is 
devoted  mainly  to  a  description  of  the  operations 
employed  in  making  American  cheddar  cheese  un- 
der normal  conditions,  including  the  care  of  cheese, 
factory  construction,  equipment,  etc.  This  portion 
of  the  subject  is  placed  first  in  order  in  the  book, 
as  a  matter  of  convenience,  because  it  is  the  por- 
tion which  will  be  most  commonly  referred  to  in 
connection  with  practical  work.  In  order  to  avoid 
overloading  the  description  of  methods  of  cheese- 
making  with  too  many  details  in  the  way  of  ex- 
planations, precautions,  etc.,  many  of  these  points 
are  discussed  with  fullness  in  later  portions  of  the 
book,  appropriate  references  being  given  in  part 


PREFACE  IX 

first.  The  second  part  is  devoted  to  a  study  of  the 
various  defects  that  may  occur  in  cheese  as  the 
result  of  abnormal  conditions  in  the  process  of 
cheese-making.  The  third  part,  which  comprises 
more  than  one-half  of  the  book,  is  devoted  to  the 
science  of  cheese-making.  This  is  the  first  attempt 
to  treat  the  subject  in  a  comprehensive,  systematic 
manner.  It  is  realized  that  not  all  of  the  chapters 
will  appeal  equally  to  those  who  use  the  book.  For 
a  satisfactory  understanding  of  Chapter  XXIV, 
some  knowledge  of  chemistry  is  required.  The 
fourth  part  of  the  book  contains  a  description  of 
methods  of  making  some  other  varieties  of  cheese 
than  American  cheddar.  In  the  fifth  and  last  part 
are  given  a  description  of  the  tests  used  in  cheese- 
making,  an  indexed  bibliography  of  the  subject,  and 
other  matter  of  a  miscellaneous  character. 

Each  illustration  has  been  carefully  selected  with 
reference  to  giving  supplementary,  helpful,  and 
specific  information.  .The  use  of  illustrations  as  a 
means  of  padding  the  book,  or  as  a  source  of  en- 
tertainment without  reference  to  the  subject-mat- 
ter, has  been  carefully  avoided. 

In  using  this  book,  teachers  will  adapt  it  to  the 
special  conditions  under  which  they  work  or  to 
the  special  purpose  they  have  in  mind.  For  ex- 
ample, the  amount  and  kind  of  matter  studied  will 
differ  in  the  case  of  short-course  and  of  long-course 
students.  Material  will  be  found  for  those  most  ad- 
vanced, as  well  as  for  beginners.  Good  judgment 
will  need  to  be  exercised  in  respect  to  the  combi- 
nation of  the  different  parts,  but  assistance  in  this 
respect  is  given  by  means  of  specific  references.  It 


X  PREFACE 

is  not  expected  that  any  book,  however  complete 
and  clear,  will  enable  one  to  make  cheddar  cheese 
successfully  without  the  help  of  a  competent 
teacher. 

It  is  appreciated  that,  in  the  preparation  of  a 
work  on  new  lines,  the  results  are  inevitably  far 
from  perfect.  Those  who  have  occasion  to  use  this 
book  will  confer  a  favor  if  they  will  be  free  to  call 
the  attention  of  the  authors  to  any  defects  which 
they  find,  whether  in  the  line  of  omissions,  incom- 
plete treatment  or  inaccuracy  of  statement. 

As  to  the  respective  shares  of  the  work  for  which 
the  authors  are  severally  responsible,  Chapters  II, 
III,  IV,  V  and  XXVII  represent  combined  work ; 
Mr.  Van  Slyke  has  written,  for  the  most  part, 
Chapters  I,  VI  and  VIII ;  Mr.  Publow,  except  for 
some  minor  changes  and  additions,  has  written 
Chapters  VII  and  IX  to  XIII  inclusive;  Mr.  Van 
Slyke  has  written  Chapters  XIV  to  XXVI  inclu- 
sive, and  also  Chapters  XXVIII  to  XXX. 

We  desire  here  to  express  our  appreciation  of 
valuable  assistance  received  in  various  ways  from 
the  following1  persons :  Mr.  G.  G.  Publow,  King- 
ston, Ontario,  Canada,  Chief  Dairy  Instructor  in 
cheese-making;  Mr.  George  A.  Smith,  Geneva, 
N.  Y.,  Dairy  Expert  at  the  New  York  Agricultural 
Experiment  Station;  Mr.  Alfred  W.  Bosworth, 
Geneva,  N.  Y.,  Associate  Chemist  at  the  New  York 
Agricultural  Experiment  Station;  and  Dr.  Donald 
D.  Van  Slyke,  New  York  City,  Assistant  Chemist 
at  the  Rockefeller  Institute  for  Medical  Research. 

September,  1908. 


CONTENTS 


PART  I. 

Page 

The  Manufacture  of  American  Cheddar  Cheese. 

I. 
The  Care  of  Milk  for  Cheese-Making        .        ....          3 

II. 

Preliminary  Steps  in  Making  Cheddar  Cheese  .         .         15 

III. 
Operations  from  Cutting  Curd  to  Salting  ....        25 

IV. 
Operations  from  Salting  Curd  to  Removal  from  Press      .        37 

V. 
Moisture  and  Acidity  in  Curd  and  Cheese:   Conditions, 

Effects  and  Control     .        .        .  .        .        .        45 

VI. 
Modifications  of  Cheddar    Process    and    Miscellaneous 

Subjects  ........        55 

VII. 
Care,  Shipment  and  Sale  of  Cheese  ....        71 

VIII. 
Commercial  Oualities  of  Cheddar  Cheese  and  Methods  of 

Judging  ~ 80 

IX. 
Cheese-Factory  Construction 97 

X. 

Cheese-Factory  Equipment       .        .        .        .        .        .       106 

xi 


xil  TABLE    OF    CONTENTS 

Page 

PART  II. 

Defects  of  American  Cheddar  Cheese:    Causes, 
Remedies  and  Means  of  Prevention. 

XL 
Defects  in  Flavor 115 

XII 
Defects  in  Body  and  in  Texture 121 

XIII. 
Defects  in  Color  and  in  Finish  ......       129 

PART  III. 

The  Science  of  Cheese-Making  :  The  Chemical,  Bio- 
logical and  Other  Relations  of  Milk  and  Cheese. 

XIV. 
The  Constituents  of  Milk 139 

XV. 

Conditions  Affecting  Proportions  of  Constituents  in  Milk  .       155 

XVI. 

Functions  of  Milk  Constituents  in  Cheese-Making    .         .       177 

XVII. 
Milk  Constituents  and  Yield  of  Cheese      ...  186 

XVIII. 
Methods  of  Calculating,  Yield  of  Cheese    .        .        .         .211 

XIX. 

Milk  Constituents  in  Relation  to  Composition  of  Cheese  .      -231 

XX. 

The  Composition  of  Cheese  in  Relation  to  Quality   .         .       243 

XXI. 

Methods  of  Paying  for  Milk  for  Cheese- Making       .         .       253 


TABLE    OF    CONTENTS  Xlll 

Page 
XXII. 

The  Relations  of  Micro-Organisms  and  Enzvms  to  Cheese- 
Making          .         .         .      ...         .        .         .         .  285 

XXIII. 
The  Ripening  of  Cheese 313 

XXIV. 
Chemical  Changes  in  Cheese-Ripening     ....       3?7 

XXV. 

Causes  of  Chemical  Changes  in  Cheese-Ripening     .         .      354 

XXVI. 
Commercial  Relations  of  Cheese-Ripening       .        .         .      379 

PART  IV. 

XXVII. 
Methods  of  Making  Different  Varieties  of  Cheese     .         .      397 

PART  V. 

*      Methods  of  Testing,  Factory  Organization 
and  Literature. 

XXVIII. 
Methods  of  Testing  Used  in  Cheese-Making     .        .        .423 

XXIX. 
Cheese-Factory  Organization  ajid  Management        .         ,       447 

XXX. 

The  Literature  of  Cheese-Making     ....  454 


ILLUSTRATIONS 


Page 

American  Cheddar  Cheese    .      .      .      .      .      .        Frontispiece 

Microscopic  Appearance  of  Clean  Milk 4 

Microscopic  Appearance  of  Unclean  Milk       ....  4 

Sanitary  Milkmg-Pails         .      .10 

Aerator  and  Cooler         .     . .  11 

Dipper  for  Use  in  Cheese-Making         ......  20 

McPherson  Hand-Agitator  for  Stirring  Curd        ...  28 

Double-Toothed  Curd-Rake 29 

Effect  of  Excessive  Moisture  in  Soaked-Curd  Cheese   .  58 

Abnormal  Texture  of  Soaked-Curd  Cheese    ....  59 

Weighing,  Paraffining  and  Boxing  Cheese      .      .      .,  •  .  74 

Apparatus  for  Paraffining  Cheese         ......  75 

Appearance  of  Perfect  Cheese-Box 78 

Close-Textured  Cheese 84 

Loose-Textured  Cheese 84 

Texture  of  Sweet -Curd  Cheese        .......  84 

Texture  Caused  by  Gas 85 

Mechanical  Holes  in  Cheese 85 

Swiss-Holes 86 

Design  for  Septic  Tanks .      .  101 

Cold-Air  Circulation  in  Curing-Room 102 

Plan  Showing  Arrangement  of  Cheese-Factory  Equip- 
ment          103 

Plan  for  Cheese-Factory 105 

Steel  Cheese-Vat 107 

Barnard's  Curd-Cutter         108 

Gosselin  Curd-Mill 108 

Continuous-Pressure  Gang-Press 109 

Fraser  and  Wilson  Hoops 110 

Apparatus  for  Showing  Humidity  in  Air        .      .      .       ,  111 

Fish-Eye  Texture  in  Yeasty  Cheese 126 

Seamy  Color  and  Lack  of  Pressure 131 

Brine-Soluble  Protein  of  Cheese  Drawn  out  in  Strings  .  148 

Diagram  Showing  Composition  of  Milk 195 

Distribution  of  Milk-Constituents  in  Cheese  and  Whey  196 

Yield  and  Composition  of  Cheese  from  Different  Milks  206 
Yield  and  Composition  of  Cheese  from  Milks  of  Different 

Breeds 208 


XVI  ILLUSTRATIONS 

Page 
Effect  of  Skimming  Milk  on  Composition  and  Yield  of 

Cheese 235 

Ball-Shaped  Bacteria 287 

Chains  of  Ball-Shaped  Bacteria 287 

Rod-Shaped  Bacteria 288 

Bacteria  with  Swimming  Hairs 288 

Effect  of  Temperature  on  Bacteria 290 

Lactic  Acid  Bacteria 292 

Close-Textured  Cheese  Ripened  at  Different  Tempera- 
tures          324 

Sweet -Curd  Cheese  Ripened  at  Different  Temperatures  325 
Devices  for  Keeping  Records  of  Temperature     .      .    384-385 

Appearance  of  Frozen  Cheddar  Cheese 390 

Edam  Press-Mold  and  Cover    .      .    * 412 

Cross-Section  of  Edam  Press-Mold  and  Cover    .      .      .  413 

Edam  Salting-Mold  in  Cross-Section 413 

Edam  Salting-Mold,  Inside  and  Outside  Appearance     .  414 

Parts  of  Gouda  Mold  Shown  Separately         .      .      .      .  418 

Parts  of  Gouda  Mold  United 418 


Part  I 

The  Manufacture  of  American 
Cheddar  Cheese 

Details  of  cheese-making  operations 
from  care  of  milk  to  sale  of  cheese. 

Commercial  qualities   and   methods 
of  judging. 

Cheese  -  factory     construction     and 
equipment. 


The  Science  and  Practice  of 
Cheese-Making 


CHAPTER  I 

The  Care  of  Milk  for  Cheese-Making 

ONE  of  the  fundamental  requisites  of  successful 
cheese-making  is  clean  milk.  The  cheese-making 
process  begins  in  reality  on  the  premises  of  the  milk 
producer;  and,  of  all  the  details  of  the  process,  the 
one  that  is,  and  has  always  been,  productive  of  most 
trouble  is  the  improper  handling  of  milk  by  patrons. 
There  has  usually  been  complete  absence  of  any  ade- 
quate method  in  caring  for  milk.  The  occasional 
skimming  or  watering  of  milk  always  calls  forth  the 
severest  condemnation,  and  properly ;  but  actual  losses 
caused  dairymen  in  this  way  are  insignificant  in  com- 
parison with  the  losses  caused  by  carelessness  and 
neglect  in  properly  caring  for  milk.  It  is  to  be  hoped 
that  the  time  may  come  when  deliberate  carelessness 
and  indifference  in  the  production  and  care  of  milk 
will  be  regarded  as  little  short  of  criminal.  The  value 
of  milk  in  cheese-making  depends,  in  no  small  degree, 
on  the  care  it  receives  from  the  time  it  is  drawn  from 
the  udder  until  it  is  delivered  at  the  factory.  The 
quality  of  milk  in  respect  to  its  cleanliness  determines, 
to  a  great  extent,  the  quality  of  cheese  that  can  be 
made  from  it. 


4        SCIENCE  ^  AND v   RRACTICE     OF     CHEESE-MAKING 


When  milk  is  not  properly  cared  for  by  patrons,  it 
may  acquire  undesirable  characteristics,  which  injure 
its  usefulness  in  cheese-making,  such,  for  example,  as 
high  acidity,  offensive  odors  and  tastes,  formation  of 
gases,  etc. 

The  causes  of  these  defects  will  be  briefly  con- 
sidered under  four  headings:  (i)  Bacterial  infec- 
tion, (2)  absorption  of  flavors,  (3)  food  eaten,  (4) 
physiological  or  disease  processes  in  cows. 


c 

«o:««>o;>v>    «.-.flfT?'? ° 

a 


00   ° 

o  • 

FIG.  1  FIG,  2 

Appearance  of  clean  milk  under  Appearance  of  unclean  milk  under  the 
the  microscope.  Only  fat-globules  microscope.  The  light,  round  bodies  are 
are  seen.  fat-globules ;  the  dark  masses  are  groups 

of  bacteria  and  cellular  matter. 


SOURCES  OF  BACTERIAL  INFECTION 

Milk,  when  drawn  with  careful  precautions  from 
the  udder  of  a  cow,  contains  comparatively  few 
bacteria;  but  milk  obtained  and  handled  under  ordi- 
nary conditions  is  found  to  contain  large  numbers, 
often  several  hundred  thousand,  in  one  cubic  centi- 
meter (somewhat  less  than  one-quarter  of  an  ordinary 
teaspoonful).  The  more  dirt  there  is  in  milk,  the 


CARE    OF    MILK    FOR    CHEESE-MAKING  5 

more  bacteria  there  will  be.  Bacteria  and  dirt  always 
go  together  in  dairy  matters.  The  relations  of  bac- 
teria to  milk  are  considered  in  greater  detail  in 
Chapter  XXII,  p.  285. 

The  most  common  sources  of  bacterial  infection  are 
the  following:  (i)  Unclean  or  unhealthy  condition 
of  cows;  (2)  unclean  condition  of  stables  or  places  of 
milking;  (3)  unclean  condition  of  persons  milking 
cows;  (4)  unclean  condition  of  utensils  used;  (5) 
keeping  milk  in  unclean  surroundings,  and  especially 
at  temperatures  above  60°  F.  after  milking. 

Unclean  condition  of  cows. — The  hair  on  cows 
favors  the  accumulation  of  dirt  and  dust.  The  con- 
dition is  worse  in  proportion  as  cows  are  not  regu- 
larly and  thoroughly  cleaned.  Dust  particles  and 
hairs,  laden  with  bacteria,  are  in  position  to  drop  into 
the  milk-pail.  While  the  hairs  and  coarse  chunks  of 
dirt  may  be  removed  from  milk  by  straining,  the 
bacteria  are,  in  large  part,  washed  off  into  the  milk 
and  cannot  be  removed  by  any  ordinary  process  of 
straining. 

Unclean  condition  of  stable. — A  dirty  condition 
of  the  floors,  walls  and  ceilings  of  a  stable  tends  to 
contaminate  milk.  Any  condition  in  the  stable  that 
affords  a  supply  of  floating  dust  at  the  time  of  milking 
furnishes  additional  bacteria  for  milk 

Unclean  condition  of  milker. — The  hands  and 
clothing  of  a  milker  may  easily  be  loaded  with  bacteria 
and  thus  become  a  source  of  infection.  Particularly 
objectionable  is  the  filthy  practice  of  moistening  the 
hands  with  milk  when  milking. 

Unclean  utensils,  especially  the  milk-pails,  strain- 
ers and  milk-cans.  The  cracks  and  joints  of  all 


6         SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

utensils  made  of  tin,  unless  great  care  in  cleaning  is 
used,  contain  dirt  that  holds  large  numbers  of  bacteria. 
Rust  and  imperfect  soldering  of  joints  furnish  places 
for  dirt  to  get  out  of  easy  reach.  Without  prompt 
and  extreme  care,  strainers  easily  become  filthy  and 
are  then  simply  breeding  places  for  bacteria.  When 
milk  cans  are  used  for  carrying  back  whey  to  the  farm 
from  the  cheese-factory,  the  cans  often  are  not  cleaned 
promptly,  and,  when  finally  attended  to,  are  not  treated 
with  proper  thoroughness.  Through  the  medium  of 
a  dirty  whey-vat,  filth,  as  well  as  disease,  germs 
may  be  distributed  throughout  the  whole  neighbor- 
hood. Even  epidemics  of  typhoid  fever  have  been 
traced  to  this  source  of  infection;  certain  diseases 
have  been  similarly  distributed  among  farm  ani- 
mals, as,  for  example,  tuberculosis  in  calves  and 
hogs. 

Unclean  surroundings  after  milking. — Milk,  even 
when  drawn  under  the  cleanest  possible  conditions, 
very  easily  becomes  contaminated  by  being  kept,  even 
for  a  short  time,  in  any  place  that  is  not  clean. 

Keeping  milk  cool. — At  temperatures  above  60° 
F.,  milk  more  rapidly  undergoes  fermentation  changes 
than  at  lower  temperatures  (p.  290). 

ABSORPTION  OF  FLAVORS 

Milk,  particularly  when  warm,  possesses  remarkable 
ability  to  absorb  and  retain  odors  present  in  the  sur- 
rounding air.  The  most  common  sources,  of  such 
odors  are  the  manure  in  unclean  stables  and  any 
strong-smelling  food  present  in  the  stable  during  milk- 
ing-time.  Among  the  most  common  conditions  under 


CARE    OF    MILK    FOR    CHEESE-MAKING  7 

which  undesirable  flavors  are  absorbed  are  the  keep- 
ing of  milk  in  or  near  cellars,  silos,  stables,  pig-pens,  or 
any  place  where  strong-smelling  substances  of  any 
kind  are  present. 

FLAVORS  FROM  FOOD  EATEN 

Certain  foods  that  have  strong  taste  and  odor  im- 
part to  milk  their  characteristic  flavors  when  eaten 
within  a  few  hours  before  milking.  Most  common 
among  these  are  onions,  garlic,  rape,  turnips,  leeks, 
cabbages,  ragweed  and  decayed  ensilage.  Experi- 
ments have  shown  that  with  most  of  these  the  effects 
are  largely,  if  not  entirely,  avoided  when  milk  is  not 
drawn  for  8  to  12  hours  after  such  food  is  eaten, 
provided  an  abnormal  amount  has  not  been  taken. 
Similar  results,  but  in  milder  form,  may  come  from 
the  feeding  of  excessive  quantities  of  such  materials 
as  swill,  brewers'  grains  and  distillery  slops.  It  is 
a  safe  rule,  in  the  case  of  milk  to  be  used  for  cheese, 
not  to  use  at  all  such  foods  as  are  in  danger  of  taint- 
ing milk,  such  as  turnips,  cabbages,  rape,  etc.,  and  to 
keep  cows  where  they  cannot  get  at  anything  that 
may  endanger  the  quality  of  the  milk  for  cheese- 
making.  Some  green  fodders,  like  second-growth 
clover,  rye,  etc.,  have  been  found  to  produce  gassy 
and  tainted  milk  and  cheese.  Such  a  condition  is 
more  likely  due  to  bacteria  on  these  foods  than  to 
any  peculiar  property  in  the  foods  themselves. 

There  is  one  marked  point  of  difference  between 
bad  flavors  of  bacterial  origin  and  those  coming  from 
absorbed  flavors  and  strong-smelling  food.  The 
latter  manifest  their  presence  in  the  milk  clearly 


8         SCIENCE     AND     PRACTICE     OF     CHEESE-MAKING 

when  the  milk  is  delivered  at  the  factory  and  may 
be  largely  removed  by  proper  aeration  and  care 
in  the  cheese-making  operations;  but  those  of 
bacterial  origin  do  not  usually  reveal  their  presence 
until  the  cheese-making  process  is  well  along,  or  not 
even  until  the  cheese  has  been  made  and  acquired 
some  age. 

PHYSIOLOGICAL  OR  DISEASE  PROCESSES 
IN  COWS 

It  is  well  known  that  if  a  cow  is  abnormally 
heated  or  excited  just  before  milking,  tainted  milk 
and  cheese  may  result.  Such  a  condition  may  be 
brought  about  by  dogging  cows  or  any  form  of 
ill  treatment.  Many  diseases  directly  affect  cow's 
milk  and  render  it  unfit  for  use  in  making  cheese. 

HOW   TO   OBTAIN   CLEAN   MILK 

We  have  seen  that  the  one  chief  source  of  bacteria 
is  dirt.  Hence,  the  one  thing  needful  to  prevent 
bacteria  getting  into  milk  is  extreme  cleanliness  at 
every  point  of  contact  with  the  milk.  The  following 
suggestions  are  given  to  indicate  what  is  meant  by 
cleanliness  in  connection  with  milking  and  caring  for 
milk. 

Cows  should  be  clean  and  healthy. — Too  much 
pains  cannot  be  taken  to  keep  cows  clean.  In  ad- 
dition to  regular  currying  and  brushing  all  over,  the 
udder  and  adjacent  portions  of  the  body  should  be 
carefully  brushed  before  milking  and  also  wiped  with 
a  damp,  clean  cloth.  The  udder  should  also  be  wiped 


CARE    OF    MILK    FOR    CHEESE-MAKING  9 

after  milking.  .  The  best  way  to  clean  the  parts  is  by 
using  warm  water  and  a  cloth.  The  cleaning  is  made 
easier  by  clipping  the  hair  close  to  the  abdomen,  udder 
and  flanks.  Dry-brushing  of  the  udder  before  milking 
should  not  be  practiced,  as  it  makes  conditions  worse 
by  stirring  up  dust  which  settles  into  the  milk-pail. 

The  stable. — Every  condition  about  the  stable 
should  be  regulated  with  reference  to  absence  of  dirt, 
an  abundant  supply  of  pure  air,  and  a  direct  exposure 
to  sunlight.  The  floors  should  be  tight  and  of  a  ma- 
terial not  readily  absorbing  liquids.  An  abundance  of 
clean  bedding  should  be  used,  and  the  manure  should 
be  removed  more  frequently  than  once  a  day,  and,  in. 
any  case,  not  immediately  before  milking.  The  walls 
and  ceiling  should  be  swept  often  enough  to  prevent 
the  accumulation  of  dust,  but  never  just  before  milk- 
ing-time.  Once  a  year,  at  least,  it  is  wise  to  clean 
the  entire  stable  with  extreme  care  and  then  go  over 
the  whole  with  a  generous  coat  of  whitewash.  At 
such  a  time  the  stable  should  be  thoroughly  disin- 
fected if  there  has  been  any  contagious  disease  in 
the  stable.  The  surroundings  outside  of  the  stable 
should  be  kept  in  a  clean  condition,  so  as  not  to  in- 
terfere with  the  supply  of  pure  air.  Where  water 
pressure  can  be  had,  as  in  case  of  a  windmill,  storage 
tank,  etc.,  hose  should  be  used  in  cleaning. 

Milking. — The  milker  should  wash  his  hands  care- 
fully before  milking  and  have  them  perfectly  dry  while 
milking.  It  is  also  desirable  to  have  a  special  coat  or 
jacket  for  milking,  made  of  some  material  that  will 
not  catch  or  hold  dust  easily.  Only  small-top  milking- 
pails  should  be  used.  (Fig.  3.) 


IO       SCIENCE     AND     PRACTICE     OF     CHEESE-MAKING 

Cleaning  dairy  utensils. — All  utensils  that  come 
in  contact  with  the  milk,  such  as  milk-pails,  milk-cans, 
aerators,  etc.,  should  be  made  of  metal,  preferably  of 
pressed  tin,  with  smooth,  well-flushed  joints  and  per- 
fect seams.  They  should  be  kept  entirely  free  from 
rust.  Such  vessels  should  never  he  allowed  to  dry 
when  dirty,  as  dried  particles  of  milk  are  particularly 
difficult  to  remove.  In  cleaning  dairy  utensils,  rinse 
them  first  with  cold  or  lukewarm  water;  and  then 
scrub  with  a  brush,  using  water  containing  some  good 
washing-powder  that  will  remove  grease.  Then  scald 


FJG.  3 — DIFFERENT  STYLES    OF  SANITARY    MILKING-PAILS 

with  boiling  water  and  complete  the  cleansing,  if  pos- 
sible, by  exposing  to  a  jet  of  live  steam  for  three  to 
five  minutes.  Never  dry  with  a  cloth,  but,  when 
practicable,  expose  the  utensils  finally  to  direct  sun- 
light for  a  few  hours.  Dust  and  flies  should  be  pre- 
vented from  entering  the  cans  after  washing. 
Strainers  should  be  washed  immediately  after 
using,  cleaning  first  in  tepid  water,  following  with 
hot  water  and  soap  or  washing-powder  and^  finally 
with  hot  water  and  then  with  steaming  or  boiling. 

Treatment   of  milk   after   milking.— As   soon   as 
each  cow  is  milked,  the  milk  should  be  removed  from 


CARE    OF    MILK    FOR    CHEESE-MAKING 


II 


the  stable  to  some  room  free  from  all  odors  and 
with  cleanly  surroundings.  The  milk  should  be  at 
once  strained  through  a  brass-wire  strainer,  having 
not  less  than  fifty  meshes  to  the  inch,  and  also 
through  three  or  four  thicknesses  of  cheese-cloth.  Still 


FIG.  4 

A  quick  way  of  cooling  milk.    The  milk  in  a  thin 


FIG.  5 
The  milk  contained  in 


/ayer  runs  over  a  surface  made  cold  by  running  ice-  these  long  "shot-gun"  pails 
water.  The  same  water  can  be  used  repeatedly  by  or  cans,placed  in  ice-water 
adding  ice  each  time.  This  method  should  be  used  is  stirred  occasionally  to 


adding  ice  each  time.    This  method  should  be 
only  when  the  surrounding  air  Is  pure. 


occasionally 
insure  even  cooling. 


more  effective  results  in  straining  can  be  secured  by 
the  use  of  absorbent  cotton,  though  its  expense  may 
make  its  use  impracticable  under  ordinary  conditions. 
After  straining,  cool  at  once  to  60°  F.,  or  better  to 
50°  F.,  by  ice  or  cold  water.  (Figs.  4  and  5.) 


12      SCIENCE     AND     PRACTICE     OF     CHEESE-MAKING 

Under  usual  conditions,  it  is  best  to  cool  the  milk 
with  as  little  exposure  to  air  as  possible  and  then  cover 
it  when  milking  is  completed. 

Aeration,  if  needed  (p.  120),  should  be  carefully  per- 
formed as  follows  for  the  best  results :  ( i )  Aeration 
should  take  place  only  in  a  pure  atmosphere.  (2)  Aera- 
tion should  be  performed  at  body  temperature  and 
therefore  is  best  done  immediately  after  milking.  (3) 
Aeration  should  precede  cooling  and  not  be  simultan- 
eous with  it.  (4)  Aeration  should  be  carried  out  over 
the  most  extensive  surface  possible  and  as  slowly  as 
possible.  Under  ordinary  farm  conditions  aeration  is 
better  not  attempted. 

Feeding-time. — Foods  having  marked  odors  should 
be  fed  only  after  milking  and  then  at  once,  and  none 
should  be  left  in  the  stable.  Dry  fodders,  which 
furnish  dust,  should  likewise  be  fed  after  milking. 

Diseased  milk. — The  milk  of  diseased  animals 
should  not  be  used  nor  that  of  animals  fresh  in  milk 
before  the  ninth  milking.  Colostrum  milk  (p.  158) 
should  never  be  used  for  cheese-making.  The  presence 
of  such  milk  seriously  affects  the  operations  of  cheese- 
making  in  the  following  manner :  Soon  after  cutting, 
the  curd  becomes  softer  and  will  not  firm  sufficiently 
to  make  good  cheese. 

Contagious  diseases. — No  person  suffering  from, 
or  recovering  from,  a  contagious  disease,  nor  any  per- 
son that  has  anything  to  do  in  caring  for  such  a 
person,  should  be  allowed  to  have  any  contact  with 
the  dairy. 

.  JUDGING  MILK  FOR  CHEESE-MAKING 

The  only  solution  of  the  problem  of  obtaining  clean 
milk  for  cheese-making  lies  in  the  education  of  the 


CARE    OF     MILK    FOR    CHEESE-MAKING  13 

milk  producer.  It  is  necessary  to  do  more  than  dis- 
tribute printed  instructions.  Personal  inspection  of 
individual  farm  premises  is  also  necessary.  But  it  is 
essential,  in  addition  to  these  methods  of  education, 
to  give  some  additional  specific  inducement  which  will 
impress  each  patron  as  nothing  else  will  and  lead  him 
to  recognize  not  only  the  general  importance  of  pro- 
ducing clean  milk,  but  the  application  to  him  person- 
ally. The  most  effective  means  of  making  a  deep 
impression  is  to  give  each  one  an  opportunity  to  see 
how  far  his  milk  departs  from  the  recognized  standard 
of  milk  that  is  clean  enough  for  making  good  cheese. 
These  results  can  be  realized  by  the  introduction  of  a 
system  of  judging  milk;  and  if  the  results  of  each 
judging  can  be  made  to  affect  the  dividends,  the  pa- 
tron soon  realizes  how  near  or  how  far  from  the 
proper  standard  his  milk  is. 

The  following  method  is  suggested  as  an  effective 
one  in  judging  cheese-factory  milk:  Examine  the 
milk  for  (i)  acidity,  (p.  426);  (2)  dirt  in  suspen- 
sion, (p.  434)  ;  (3)  micro-organisms  by  the  fermen- 
tation test,  (p.  434)  ;  and  (4)  flavor.  Use  the  fol- 
lowing scale  of  points  for  scoring  milk: 

When  perfect 

Acidity IS 

(Acidity  not  over  0.18  per  cent.) 

Dirt 15 

(No  dirt  in  suspension.) 

Fermentation  test 45 

(No  signs  of  abnormal  ferments.) 
Flavor 25 

(Entire  freedom  from  abnormal  odor  and  taste.) 

In  each  milk,  the  score  is  diminished  in  the  case  of 
each  quality  if  the  milk  shows  any  imperfections.  This 
system  will  be  found  effective  in  application,  if  the 


14      SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

judging  is  done  carefully  and  the  results  made  known 
to  the  patrons.  If  patrons  can  be  persuaded  to  apply 
the  results  of  such  judging  to  the  distribution  of  divi- 
dends, the  work  would  be  more  effective,  of  course. 
For  example,  a  patron's  dividend  could  be  marked 
down  one  cent  per  100  pounds  of  milk  for  each  ten 
points  his  milk  scored  below  100  on  the  above  system. 
Of  course,  this  method  does  not  apply  to  cases  in 
which  the  milk  is  obviously  bad  when  brought  to  the 
factory.  The  only  remedy  in  such  cases  is  to  refuse 
the  milk  altogether. 

This  is  a  matter  which  should  be  discussed  at  the 
annual  meeting  of  patrons,  in  case  of  co-operative 
factories,  when  some  definite  policy  should  be  adopted 
and  intelligently  enforced.  For  a  more  complete  treat- 
ment of  the  subject  of  judging  and  scoring  milk,  see 
Modern  Methods  of  Testing  Milk  and  Milk  Products, 
pp.  182-192  (published  by  the  Orange  Judd  Co.). 


CHAPTER  II 

Preliminary  Steps  in  Making 
Cheddar  Cheese 

IN  entering  upon  the  detailed  study  of  the  methods 
of  cheese-making,  we  shall  present  the  subject  in  ac- 
cordance with  the  following  outline  of  the  different 
steps  in  the  various  operations  that  are  performed: 

(1)  System  of  keeping  records  of  the  operations  of 
cheese-making. 

2)  First  care  of  milk  at  the  factory. 

3)  Ripening  the  milk. 

4)  Adding  color. 

5)  Coagulating  the  milk  by  rennet. 

6)  Cutting  the  curd. 
?7)  Heating  the  curd. 

(8)  Removing  the  whey  from  the  curd. 

(9)  Cheddaring  the  curd. 

(10)  Milling  the  curd. 

(11)  Salting  and  pressing  curd  and  dressing  cheese. 

(12)  Care,  shipment  and  sale  of  cheese. 

In  describing  the  details  of  the  methods  of  making 
American  cheddar  cheese,  we  shall  limit  our  treatment 
largely  to  normal  conditions,  reserving  for  separate 
treatment  abnormal  conditions  (p.  115).  An 
effort  is  made  not  to  overload  the  description  with 
unnecessary  details.  The  explanation  of  many  de- 
tails is  given  in  other  chapters,  to  which  reference 
will  be  made  as  needed,  instead  of  incorporating 
them  with  the  description  of  the  cheese-making 
operations. 


j6         SCIENCE  AND  PRACTICE   OF   CHEESE-MAKING 

SYSTEM    OF    KEEPING    RECORD    OF    THE 
OPERATIONS  OF  CHEESE-MAKING 

Few  manufacturing  processes  require  more  careful 
and  more  skilled  mechanical  manipulation  than  does 
cheese-making ;  none  demands  more  responsibility  and 
intelligence.  A  successful  cheese-maker  must  be  quick 
to  think  and  to  act;  he  must  know  the  details  of 
his  process  and  the  principles  underlying  these  de- 
tails, and  be  able  to  apply  his  knowledge  in  con- 
trolling variations  caused  by  climatic,  biological  and 
chemical  conditions.  In  beginning  his  daily  work, 
a  maker  should  have  clearly  in  mind  the  ideal 
he  wishes  to  realize  in  the  finished  cheese,  and 
should  conduct  his  work  with  this  end  in  view.  It  is 
absolutely  essential  to  the  highest  success  to  keep  daily 
records  of  the  details  of  the  work  for  constant  refer- 
ence. Below,  we  give  a  detailed  blank  form,  and 
advise  all  cheese-makers  and  students  of  cheese- 
making  to  make  constant  and  faithful  use  of  it  in 
their  daily  work: 

1.  Vat  used  (number  of  vat). 

2.  Condition  of  milk  (flavor,  temperature,  acidity). 

3.  Amount  of  milk  in  vat pounds. 

4.  Fat  in  milk per  cent.          Casein  in  milk per  cent. 

5.  Ripeness  of  milk  by — 

1.  Acidity-test per  cent  of  acidity. 

2.  Marschall  rennet-test spaces. 

3.  Monrad  rennet- test seconds. 

6.  Kind  of  starter  used Acidity per  cent. 

7.  Amount  of  starter  used pounds. 

8.  Time  when  starter  was  added a.  m.         p.  m. 

9.  Amount  of  color  added. 

10.  Kind  of  color  used. 

11.  Temperature  of  milk  when  rennet  was  added degrees  F. 

12.  Ripeness  of  milk  when  rennet  was  added — 

1.  By  rennet-test seconds  or      spaces 

2.  By  acidity-test per  cent. 

13.  Time  when  rennet  was  added a.  m.         p.  m. 

14.  Amount  of  rennet  (or  pepsin)  used ounces  or  grams. 

15.  Amount  of  rennet  (or  pepsin)  used  per  1,000  pounds  of 

milk ounces  or        grams. 

16.  Time  when  curd  was  cut a.  m.         p.  m. 

1 7.  Time  in  coagulating minutes. 


FIRST   STEPS  IN   CHEESE-MAKING 


18.  Condition  of  curd  when  cut  (hard,  soft,  etc.). 

19.  Time  when  heating  began  ...........................  a.  m.         p.  m. 

20.  Acidity-  test  of  whey  when  heating  began  ....................  per  cent. 

21.  Temperature  to  which  milk  was  heated  after  cutting,  etc  ......  degrees  F. 

22.  Time  at  which  temperature  was  reached  ..............  a.  m.         p.  m. 

23.  Test  when  whey  was  removed  — 

1.  By  hot-iron  test  .....................................  inches. 

2.  By  acidity-test  ..............................  .  ......  per  cent. 

24.  Time  at  which  whey  was  removed  ....................  a.  m.         p.  m. 

25.  Time  from  cutting  curd  to  removal  of  whey  ..........  hours         minutes 

26.  Amount  of  fat  in  whey.  ....  .......  .  ............  .  .........  per  cent. 

27.  Condition  of  curd  (sweet,  tainted,  solid,  gassy,  floating,  etc.). 

28.  Time  when  curd  was  milled  .........................  a.  m.         p.m. 

29.  Length  of  string  on  hot  iron  when  curd  was  milled  .............  inches. 

30.  Acidity-test  of  whey-drippings  when  curd  was  milled  ..........  per  cent. 

31.  Time  when  curd  was  salted  ..........................  a.  m.         p.m. 

32.  Acidity-  test  of  whey  running  from  curd  just  before  salting  .....  per  cent. 

33.  Amount  of  salt  used  for  1,000  pounds  of  milk  .................  pounds. 

34.  Kind  of  salt  used. 

35.  Time  when  curd  was  put  in  press  ....................  a.  m.         p.  m. 

36.  Temperature  of  curd  when  put  in  press  .........  ...........  degrees  F. 

37.  Condition  of  curd  when  put  in  press. 

38.  Kind  of  cheese  made. 

39.  Number  of  cheeses  made. 

40.  Time  when  cheese  was  dressed  .......................  a.  m.         p.  m. 

41.  Time  when  cheese  was  pressed  .......................  a.  m.         p.m. 

42.  Time  when  cheese  was  taken  from  press  ...............  a.  m.         p.m. 

43.  Weight  of  green  cheese  ....................................  pounds. 

44.  Average  amount  of  milk  per  pound  of  cheese  .................  pounds. 

45.  Amount  of  cheese  from  100  pounds  of  milk  ...................  pounds. 

46.  Amount  of  cheese  made  for  1  pound  of  milk-fat  ..............  pounds. 

47.  Weather  conditions  (temperature,  humidity    etc.). 

48.  Amount  of  cheese  from  100  pounds  of  milk   calculated  by 

formula  6  (p.  225). 

Special  remarks.  —  (Include  here  any  deviations  from  the  usual  modes 
of  procedure  not  included  in  the  foregoing  list.) 


FIRST  CARE  OF  MILK  AT  THE  FACTORY 

Each  can  of  milk,  on  arriving  at  the  factory,  should 
be  carefully  examined  for  acidity,  cleanliness  and  ab- 
normal flavors  (p.  426).  If  any  is  sour  or  of  bad 
flavor  it  should  not  be  accepted.  When  any  patron's 
milk  is  suspected,  from  the  results  of  these  tests,  of 
containing  ferments  that  work  harm  in  cheese-making, 
the  milk  should  be  subjected  to  the  fermentation  test 
(p.  434).  At  any  time  when  abnormal  fermentations 
make  trouble,  each  patron's  milk  should  be  thus 
treated  until  the  source  of  trouble  is  located.  For  a 
quick  test  for  acidity,  see  p.  428.  When  weighed,  the 


l8         SCIENCE  AND  PRACTICE   OF   CHEESE-MAKING 

milk  should  be  strained  through  two  layers  of  clean 
cheese-cloth  to  remove  all  insoluble  dirt  (p.  434). 
While  the  milk  is  accumulating  in  the  vat,  it  should 
be  stirred  frequently  up  to  the  time  of  coagulating 
with  rennet  in  order  to  keep  the  cream  from  separ- 
ating. When  the  vat  is  full  enough,  the  amount  of 
milk  present  is  figured,  and  the  acidity  of  the  milk 
is  determined  or  a  rennet-test  made. 

RIPENING  MILK 

This  consists  in  the  formation  of  a  certain  amount 
of  lactic  acid  (p.  292).  Its  object  is  to  control  more 
completely  the  various  operations  of  cheese-making; 
this  is  accomplished  especially  (i)  by  the  repression 
of  abnormal  ferments;  (2)  by  assistance  in  shrinking 
curd,  expelling  whey,  and  maturing  the  curd  in  body 
and  texture.  Lactic  acid  may  be  formed  by  allowing 
milk  to  stand  a  while  at  a  temperature  of  about  86°  F. 
When  lactic  acid  bacteria  are  not  present  in  abundance 
or  are  kept  back  in  growth  by  injurious  organisms,  it 
is  necessary  to  use  a  starter  or  culture. 

Preparation  of  starter. — A  starter  is  a  material 
(usually  milk),  containing  large  numbers  of  lactic 
acid  organisms,  which  is  added  to  milk  or  cream 
for  the  purpose  of  causing  lactic  fermentation.  Start- 
ers are  of  two  kinds:  (i)  Natural  and  (2)  com- 
mercial, (i)  Natural  starters. — A  natural  starter 
may  be  prepared  as  follows :  Milk  of  the  best  possible 
character,  taken  under  precautions  necessary  to  insure 
cleanliness,  is  heated  to  90°  F.  for  one  hour,  aerated  in 
a  pure  atmosphere,  and  immediately  cooled  to  65°  F. 
In  24  hours  the  milk  should  be  sufficiently  sour  to  be 
ready  for  use,  Some  of  this  starter  may  be  used  in 


FIRST   STEPS  IN   CHEESE-MAKING  19 

preparing  a  starter  for  the  following  day,  putting  a 
little  into  some  skim-milk  that  has  been  heated  to  180° 
F.  for  30  minutes,  cooled  to  70°  F.,  and  then  allowed 
to  stand  18  to  24  hours.  The  starter  may  thus  be 
propagated  from  day  to  day.  Occasionally,  almost 
pure  cultures  of  lactic  acid  bacteria  can  be  obtained 
in  this  way,  but  this  is  an  exceptional  experience. 
Results  much  more  reliable  come  from  the  use  of 
commercial  starters.  (2)  Commercial  starters. — Com- 
mercial starters  are  special  preparations  consisting  of 
certain  organisms  that  produce  lactic  acid.  These  are 
carefully  prepared  under  the  supervision  of  trained 
bacteriologists  and  sold  to  cheese-makers.  They  are 
usually  known  as  cultures  or  pure  cultures.  The 
medium  in  which  these  organisms  are  sent  out  may 
.  be  milk,  broths,  milk-sugar  or  porous  paper.  Proper 
directions,  with  necessary  precautions,  usually  ac- 
company these  commercial  preparations.  Below  is 
given  a  satisfactory  method  for  the  use  of  a  com- 
mercial preparation  in  making  a  starter  for  cheese- 
making. 

Inoculation  of  the  culture. — In  a  can  or  glass  ves- 
sel that  has  been  thoroughly  cleaned  and  sterilized 
with  boiling  water,. place  one  quart  of  clean,  sweet 
milk.  Heat  the  milk  to  at  least  185°  F.  for  one  hour 
by  placing  the  can  or  vessel  in  boiling  water.  At  the 
end  of  an  hour  cool  the  milk  rapidly  to  95°  F.  by 
setting  the  can  or  vessel  in  cold  water.  Then  add  the 
contents  of  the  small  bottle  of  a  prepared  culture  to 
the  milk,  stirring  it  in  with  a  sterilized  spoon.  Allow 
the  milk  to  cool  gradually  to  70°  F.  and  hold  at  this 
temperature  for  24  hours.  At  the  end  of  this  time 
the  milk  should  be  sour  and  coagulated. 


2O        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

Propagation  of  starter.— In  a  can  that  has  been 
thoroughly  cleaned  and  sterilized,  place  two  gallons  of 
clean,  fresh  skim-milk.  Heat  the  milk  to  185°  F.  for 
one  hour  by  setting  the  can  in  boiling  water.  Stir 
the  milk  frequently  to  insure  even  heating.  After  the 
milk  has  been  held  at  this  temperature  for  one  hour, 
it  may  be  cooled  immediately  to  70°  F.  by  placing 
the  can  in  cold  water.  Then  add  the  contents  of  the 
small  vessel  that  was  prepared  on  the  previous  day, 
stirring  it  in  with  a  sterilized  spoon.  Hold  the  tem- 


FIG.  6 — THIS  STYLE  OF  DIPPER  HAS  A  SOLID  HANDLE 
AND  IS  EASY  TO   KEEP  CLEAN  IN   EVERY  PART 

perature  at  70°  F.  for  18  hours.  At  the  end  of  this 
period  the  milk  should  be  sour  and  firmly  coagulated. 
A  uniform  starter  can  thus  be  prepared  from  day  to 
day,  always  adding  enough  of  the  coagulated  starter 
to  the  amount  of  pasteurized  skim-milk  necessary  for 
the  cheese-making  process. 

Precautions. — All  vessels,  pails,  dippers,  thermome- 
ters and  everything  with  which  the  starter-milk  comes 
in  contact  should  be  sterilized  before  being  used. 
Starters  should  not  be  prepared  from  the  milk  mixed 
in  the  vat  or  from  whey.  A  good  starter  is  an  in- 
valuable aid  in  cheese-making,  while  a  bad  one  is  a 
sure  source  of  trouble.  As  soon  as  the  starter  loses 


FIRST  STEPS  IN   CHEESE-MAKING  21 

its  clean,  nutty,  mild  aroma  and  sharp  taste,  it  should 
be  replaced  by  a  new  one. 

Use  of  starter  in  cheese-making. — The  amount  of 
starter  that  can  safely  be  used  will  depend  on  the 
amount  of  acidity  or  ripeness  of  the  milk  at  the  start. 
Generally,  from  0.5  to  2  per  cent  is  sufficient,  but,  if 
the  milk  is  very  sweet,  as  much  as  5  per  cent  can 
be  used.  In  using-  a  starter,  reject  the  upper  portion 
and  pass  the  rest  into  the  milk  through  a  fine  strainer. 
If  colored  cheese  is  being-  made,  add  the  starter  before 
the  color;  otherwise  white  spots  in  the  curd  may  be 
produced. 

Finding  proper  degree  of  ripeness. — The  proper 
degree  of  ripeness  can  be  ascertained  by  the  following 
methods : 

(i)     By  the  use  of  the  test  for  acidity  (p.  426)  ; 

(2)  by  the  use  of  the  Marschall  rennet-test  (p.  429)  ; 

(3)  by  the  use  of  the  Monrad  rennet-test  (p.  431). 

The  general  aim  of  ripening  is  to  have  such  a  degree 
of  acidity  when  the  rennet  is  added  that  the  curd  will 
remain  in  the  whey  not  more  than  2^4  to  3  hours. 
This  time  will  vary  with  the  seasons  of  the  year,  the 
important  point  being  to  have  the  curd  firmed  in  the 
whey  before  too  much  acidity  has  developed.  Usually 
when  the  acid  test  shows  0.19  to  0.21  per  cent  of 
acidity,  or  when  the  milk  coagulates  at  2^/2.  spaces  in 
the  Marschall  rennet-test,  or  in  45  to  60  seconds  by 
the  Monrad  test,  the  proper  degree  of  ripeness  has 
been  reached.  Milk  testing  over  0.21  per  cent  acidity 
when  delivered  at  the  factory  is  generally  overripe  and 
liable  to  cause  trouble ;  therefore,  it  should  not  be  ac- 
cepted, unless  most  of  the  other  milk  delivered  at 
the  time  has  considerably  less  acidity. 


22        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

ADDING  COLOR 

When  coloring-matter  is  used,  it  should  be  added 
just  before  the  rennet,  being  diluted  before  addition 
and  thoroughly  mixed  through  the  mass  of  milk.  The 
amount  used  depends  on  the  demands  of  different 
markets.  About  I  ounce  for  1,000  pounds  of  milk  is 
generally  sufficient,  but  the  amount  may  vary  from 
l/2  ounce  to  3  ounces. 

PREPARATION  AND  ADDITION  OF 
RENNET-EXTRACT 

Adding  rennet-extract  is  commonly  known  as 
"setting"  milk  with  rennet.  As  soon  as  the  milk  is 
ripe  enough  the  rennet-extract  should  be  added.  In 
the  use  of  rennet,  three  points  must  be  kept  in  mind : 
(i)  Temperature  of  milk;  (2)  amount  of  rennet- 
extract  to  use;  (3)  method  of  adding  rennet-extract 
and  thorough  stirring  after  addition. 

(1)  Temperature   of  the   milk. — The   ideal  tem- 
perature,   under    normal    conditions,    is  86°    F.,    al- 
though    many    successful     cheese-makers    prefer     a 
temperature    of    84°     F.     At    higher    temperatures 
the    curd    hardens    too    quickly    to    handle    conven- 
iently, and  there  is  danger  of  loss  of  fat  later  in  the 
cutting.     Lower  temperatures  require  a  longer  time 
for  a  proper  degree  of  hardness,  and,  if  the  extra 
time   is   not   allowed,   give   too    soft   a    curd,    which 
results    in    loss    in    cheese    yield.     The    temperature 
should  be  uniform  throughout  the  milk. 

(2)  Amount  of  rennet-extract  to  use. — This  will 
depend  on  (i)  the  strength  of  the  extract,   (2)  the 


FIRST     STEPS     IN     CHEESE-MAKING  23 

temperature  of  the  milk,  (3)  the  acidity  of  the  milk, 
(4)  the  composition  of  the  milk,  (5)  the  kind  of 
cheese  to  be  made,  and  (6)  the  temperature  of 
curing  (p.  61).  In  general,  an  amount  sufficient 
to  coagulate  the  milk  fit  for  cutting  in  25  to  35 
minutes  should  be  used.  Generally  from  2,^/2  to  4 
ounces  for  1,000  pounds  of  -milk  will  suffice. 

(3)  Method  of  adding  rennet-extract  and  subse- 
quent treatment. — Before  being  added  to  milk,  the 
rennet  should  be  diluted  with  40  times  its  volume 
of  pure,  cold  water.  The  object  of  this  is  to  enable 
one  to  distribute  the  rennet  solution  thoroughly 
and  uniformly  throughout  the  mass  of  milk  before 
the  rennet  begins  to  coagulate  the  casein.  Rennet 
acts  more  slowly  when  diluted  with  cold  water 
(p-  3°7)-  The  milk  should  be  thoroughly  stirred 
before  the  rennet  is  added.  The  diluted  rennet 
should  be  gradually  poured  the  whole  length  of 
the  vat,  and  the  milk  at  once  stirred  again  for  3 
to  5  minutes.  A  rake  may  be  used  to  advantage 
for  stirring.  Then  the  surface  is  stirred  gently  to 
keep  the  cream  from  rising.  All  motion  of  the 
milk  should  be  stopped  as  soon  as,  or  before,  coag- 
ulation starts.  The  vat  should  be  covered  to  pre- 
vent cooling  at  the  surface  and  to  keep  out  flies 
and  dust,  and  then  left  undisturbed  until  ready  for 
cutting. 

Causes  of  imperfect  coagulation. — By  imperfect 
coagulation,  we  mean  (i)  incomplete  or  delayed 
coagulation  of  casein,  shown  by  slimy  or  gelatin- 
ous appearance  of  the  coagulated  milk  and  a  curd 
containing  too  much  whey;  or  (2)  variation  in  de- 
gree of  hardness  in  different  portions  of  the  mass 


24     SCIENCE    AND     PRACTICE    OF     CHEESE-MAKING 

of  milk,  some  portions  being  too  hard  and  others 
too  soft.  Imperfect  coagulation  results  (i)  in  ex- 
cessive loss  of  fat  and  of  casein  from  the  soft  curd  and 
(2)  in  imperfect  texture  and  body  in  cheese,  due  to 
the  hard  pieces  of  curd. 

The  causes  of  imperfect  coagulation  may  be: 

(1)  For  incomplete  or  delayed  coagulation: 

(a)  Jarring  of  milk  after  coagulation  starts. 

(b)  Weak    rennet-extract    or    too    small    an    amount. 

(c)  Low  temperature,  due  to  inaccurate  thermometer 
(p.  309). 

(d)  The  presence  of  formalin  (p.  308). 

(e)  Abnormal    milk,    containing    small    percentage    of 
casein  or  small  percentage  of  calcium  salts  (p.  164). 

f)  Pasteurized  milk  (p.  310). 

;)  Presence  of  abnormal  bacterial  ferments. 

i)  Heavily  watered  milk  (p.  307). 

i)  Use  of  badly  rusted  milk-cans  (p.  309). 

(2)  For  uneven  coagulation: 

(a)  Uneven  temperature  of  milk  in  vat,  due  to  lack  of 
thorough  agitation. 

(b)  Adding  rennet  to  milk  too  soon  after  heating,  while 
the  sides  and  bottom  of  the  vat  are  still  hot.     The  curd  sticks 
to  the  sides  of  the  vat  and  makes  cutting  difficult. 

(c)  Agitation  of  milk  after  coagulation  begins. 

(d)  Uneven  distribution  of  rennet -extract. 


CHAPTER  III 

Operations  from  Cutting  Curd  to  Salting 

CUTTING  THE  CURD 

Purpose  of  cutting  curd. — The  object  of  cutting 
curd  is  to  allow  the  whey  to  escape  from  it.  The 
rapidity  of  the  escape  of  whey  increases  with  the 
smallness  of  the  pieces  of  curd. 

When  to  cut  curd. — Curd  must  be  cut  at  the 
right  stage  of  hardness.  The  stage  for  cutting  is 
ascertained  in  several  ways.  We  give  three  of 
them,  (i)  The  end  of  the  index  finger  is  inserted 
obliquely  into  curd  half  an  inch  or  more  and  then 
slowly  raised  to  surface.  If  the  curd  breaks  apart 
with  a  clean  fracture  without  leaving  small  bits 
of  curd  on  the  finger,  and  if  the  whey  in  the  broken 
surface  is.  clean  and  not  milky,  the  curd  is  ready 
to  cut.  (2)  Lay  the  back  of  the  hand,  including 
the  fingers,  on  the  surface  of  the  curd  near  the 
edge  of  the  vat  and  press  it  gently  away  from  the 
side  of  the  vat.  As  soon  as  it  will  separate  from 
the  side  of  the  vat  in  a  clean  way,  leaving  no  par- 
ticles of  curd  on  the  side  of  the  vat,  it  is  ready  to 
cut.  (3)  The  following  is  probably  the  most  ac- 
curate rule  for  determining  when  the  curd  should 
be  cut :  Two  and  one-half  times  the  period  from  add- 
ing rennet  till  the  first  thickening  appears  gives  the 
time  for  cutting. 


26        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

Example: 

Time  when  rennet  was  added,  7 130  A.  M.. 

Time  of  first  thickening,  7:40  A.  M. 

From  adding  rennet  till  first  thickening^=io  min- 
utes. 

2^/2  times  10  minutes=25  minutes. 

7:30+25=7:55. 

Time  of  cutting  is  7:55  A.  M. 

When  curd  is  cut  too  soon,  the  loss  of  fat,  and 
probably  of  casein,  is  increased  and  there  is  a 
smaller  yield  of  cheese.  If  the  curd  becomes  too 
hard,  it  cannot  be  cut  uniformly;  if  a  wire  knife 
is  then  used,  the  wires  may  break. 

How  to  cut  curd. — Uniformity  in  the  size  of 
pieces  is  the  aim  of  good  cutting.  This  can  be 
most  easily  accomplished  by  cutting  slowly  length- 
wise of  the  vat  with  a  ^-inch  steel  horizontal 
knife  having  sharp  edges.  Then  cut  crosswise 
with  a  5- 1 6-inch  perpendicular,  wire  knife.  Finally, 
cut  lengthwise  with  the  same  wire  knife.  Care 
should  be  taken  not  to  smash  the  curd  when  insert- 
ing the  knives  or  when  turning  them  at  the  ends 
of  the  vat.  The  resulting  cubes  should  be  of  uni- 
form size  to  insure  an  even  escape  of  whey,  a 
well-regulated  development  of  acidity  in  curd  and  a 
uniform  color  in  the  cheese.  Extra  losses  of  cheese 
constituents  (p.  193)  in  the  whey  are  due  to  care- 
lessness or  lack  of  skill  in  the  cutting  or  in  the  sub- 
sequent stirring.  The  knives  should  be  drawn 
straight  and  even  and  should  not  overlap  the  por- 
tions previously  cut.  The  faster  the  cutting,  the 
smaller  and  more  uneven  the  cubes  will  be. 


CUTTING    CURD   TO    SALTING  27 

Effect  of  cutting  curd  fine  or  coarse. — The  effect 
of  cutting  curd  fine  is  to  release  the  whey  more 
rapidly  and  completely  and  to  produce  a  cheese 
containing-  less  moisture.  This  fact  is  made  use 
of  in  the  handling  ,of  overripe  milk  (p.  122)  ;  the 
quick  escape  of  whey  enables  one  to  control  better 
the  acidity  in  the  curd.  Curd  must  be  heated  to 
a  certain  temperature  for  a  certain  length  of  time 
before  it  becomes  firm  enough  to  insure  good  body 
in  the  cheese.  If  the  pieces  of  curd  are  larger, 
it  takes  longer  for  the  whey  to  escape  and  longer 
for  the  pieces  to  contract  and  become  firm.  Con- 
sequently, if  knives  that  cut  coarser  are  used,  the 
rennet  must  be  added  when  the  milk  shows  less 
acidity,  in  order  to  allow  the  curd  to  remain  in  the 
whey  a  longer  time. 

Behavior  of  curd  after  being  cut. — After  the  curd 
is  cut  into  small  cubes,  a  slight  coating  or  film 
begins  to  form  on  the  outer  surface  of  each  cube. 
The  existence  of  this  film  can  be  shown  by  break- 
ing one  of  the  curd  cubes;  the  film  can  then  be 
seen.  The  inner  portion  of  the  curd  is  observed 
to  be  softer,  due  to  the  larger  amount  of  whey 
present.  It  is  important  that  this  film  should  not 
thicken  or  harden  too  rapidly  and  thus  prevent 
the  escape  of  whey  in  desired  amount.  The  sub- 
sequent operations  have  for  one  of  their  important 
objects  control  of  the  expulsion  of  whey  and  simul- 
taneous hardening  or  contracting  of  the  pieces  of 
curd.  The  contraction  or  hardening  of  the  pieces 
of  curd  is  known  as  "firming."  It  is  probably  due 
primarily  to  escape  of  whey.  What  share  tem- 
perature, rennet  and  acidity  each  has  in  the  process 
cannot  now  be  stated  definitely. 


28        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

STIRRING  CURD  AFTER  CUTTING 

If  the  curd  is  not  stirred  immediately  after  cut- 
ting, it  soon  masses  together  or  becomes  lumpy. 
To  prevent  this,  the  curd  must  be  kept  in  motion 
till  the  pieces  become  properly  firmed.  True  stir- 
ring of  the  soft,  tender  curd  should  be  very  gentle 
at  first  and  should  be  done  with  an  agitator  (Fig. 
7).  In  large  factories,  steam-power  agitators  are 
used.  After  the  pieces  of  curd  become  healed  over 
on  the  surface  by  the  formation  of  the  film  de- 


FIG.  7 — MCPHERSON  HAND-AGITATOR  FOR  STIRRING 
CURD    IMMEDIATELY   AFTER   CUTTING 

scribed  above  and  start  to  contract,  they  can  be 
stirred  and  kept  separated  more  easily  by  using  a 
wooden  rake  (Fig.  8).  The  curd  should  be  pre- 
vented from  collecting  in  the  corners  of  the  vat  and 
from  sticking  to  the  sides.  Rough  handling  of  the 
soft  curd  crushes  it  and  causes  a  severe  decrease  in 
the  yield  of  cheese,  as  the  result  of  increased  loss  of 
cheese-solids  in  the  whev. 


CUTTING    CURD   TO    SALTING  29 

HEATING  THE  CURD 

When  to  apply  heat. — The  rapidity  with  which 
the  pieces  of  curd  contract  and  the  rapidity  with 
which  the  lactic  acid  is  being  formed  determine 
the  time  at  which  the  heat  should  be  applied.  In 
any  case,  the  curd  should  be  stirred  gently  for 
some  time  after  cutting,  until  the  small  pieces  have 
healed  over,  or  formed  a  film,  and  have  contracted 
slightly.  Heat  alone  does  not  firm  the  curd.  It 
is  probably  due  to  the  combined  action  of  heat,  ren- 


FIG.    8 — DOUBLE-TOOTHED   CURD-RAKE    USED    FOR 
STIRRING  CURD  AFTER  CUTTING 

net  and  acidity.  The  firming  and  contraction  of 
curd  and  expulsion  of  whey  go  on  together.  The 
faster  the  acidity  is  increased,  the  quicker  will  the 
curd  contract.  The  action  of  heat  in  the  process  of 
contraction  enables  the  curd  to  retain  its  firmness 
and  also  prevents  the  reabsorption  of  whey. 

How  high  to  heat  curd. — The  lower  the  tempera- 
ture used  for  heating  curd,  provided  the  curd  be 
properly  firmed,  the  smoother  will  be  the  body  of 
the  cheese.  As  a  rule,  98°  to  100°  F.  will  be  high 


3O        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

enough,  but  this  can  be  varied  from  96°  F.  in  the 
springtime  to  102°  F.  in  the  fall.  Curd  from  milk 
rich  in  fat  is  harder  to  firm  than  curd  from  poor 
milk,  owing  generally  to  the  smaller  proportion 
of  casein  relative  to  fat.  Thus,  milk  containing 
3  to  3.6  per  cent  of  fat  ordinarily  behaves  at  94°  to 
96°  F.  the  same  as  milk  with  4  to  5  per  cent  of  fat 
does  at  98°  to  102°  F.  In  extreme  cases,  the 
temperature  may  have  to  be  raised  even  higher  to 
firm  successfully  the  curd  from  overripe  milk.  High 
heating  generally  causes  a  corky  or  rubbery-bodied 
cheese. 

How  to  regulate  heat. — Care  must  always  be 
taken  not  to  raise  the  temperature  of  the  curd  too 
rapidly.  Usually  the  temperature  can  be  raised 
about  2°  F.  in  every  5  minutes,  but  when  the  lactic 
acid  formation  is  slow,  i°  F.  every  5  minutes  may 
be  sufficient.  The  following  rule  is  a  reliable  guide 
in  heating: 

Rule  for  heating. — If,  after  cutting,  the  whey 
around  the  curd  shows  0.12  per  cent  acidity,  allow 
60  minutes  for  heating;  0.13  per  cent  acidity,  al- 
low 40  minutes  for  heating;  0.14  per  cent  acidity, 
allow  30  minutes  for  heating;  0.145  per  cent  acidity, 
allow  25  minutes  for  heating;  0.15  per  cent  acidity, 
allow  20  minutes  for  heating. 

It  is  noticeable  that  the  whey  at  this  stage  con- 
tains 0.05  to  0.08  per  cent  less  of  acidity  than  the 
milk  does  when  the  rennet  is  added.  This  is  due 
to  the  fact  that  the  whey  contains  no  casein  and  the 
casein  in  the  milk  has  the  power  of  acting  like  an 
acid  in  neutralizing  alkali. 


CUTTING    CURD    TO    SALTING  3! 

Applying  heat  too  fast  hardens  the  outside  of  the 
curd  and  prevents  the  escape  of  whey.  The  acid 
in  the  curd  develops  from  the  sugar  present  in  the 
whey  within  the  curd  and  not  from  the  whey  out- 
side of  the  curd,  so  that,  if  too  much  whey  is  re- 
tained in  the  curd,  too  much  acidity,  develops  and 
an  acid  or  sour  cheese  results. 


WHEN  TO  REMOVE  WHEY  FROM  CURD 

How  to  ascertain. — Several  indications  show 
when  the  whey  should  be  removed  from  the  curd, 
(i)  The  pieces  of  curd  should  be  contracted  to 
less  than  one-half  their  original  size.  (2)  They 
should  be  firm  and  rubber-like,  or  springy,  so  that 
when  a  mass  of  curd  is  pressed  between  the  hands 
and  then  suddenly  freed  from  pressure,  the  pieces 
should  fall  apart  at  once  and  show  no  tendency  to 
stick  together.  (3)  When  firm,  the  curds  should 
show  fine  threads  l/%  inch  long  when  rubbed  on  a 
clean,  hot  iron  (p.  438).  (4)  The  whey  around 
the  curd  should  have  0.16  to  0.18  per  cent  of  acid- 
ity, as  shown  by  the  acid  test.  This  will  vary 
slightly,  depending  on  the  time  required  for  re- 
moving the  whey.  The  quantity  of  milk  in  the  vat, 
the  size  of  the  outlet  of  the  vat,  and  the  condition 
of  the  curd  should  govern  the  amount  of  acidity 
developed  at  the  time  of  starting  to  remove  the 
whey.  It  is  a  good  practice  to  draw  off  the  whey 
down  to  the  level  of  the  curd  in  the  vat  a  few  min- 
utes before  sufficient  acidity  has  developed.  This 
gives  a  better  chance  to  control  the  remainder. 
The  most  accurate  rule  to  follow  is  to  have  0.24 


32        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

to  0.30  per  cent  of  acidity  in  the  whey  running 
from  the  curd  after  it  has  been  stirred  dry  enough 
and  piled  up  for  cheddaring.  The  amount  of  acidity 
developed  will  depend  on  the  character  of  cheese 
desired  and  upon  the  amount  of  moisture  left  in  the 
curd.  A  firm  export  cheese  requires  more  acidity 
and  less  moisture  than  a  quick-ripening  cheese  for 
home  trade. 

STIRRING  CURD   TO   DRY   IT 

The  proper  place  to  stir  and  to  dry  the  curd  is 
in  the  whey,  from  the  time  the  whey  has  reached 
the  curd  level  until  it  is  all  removed.  This  gives 
a  brighter  and  better  color  to  the  curd  and  re- 
quires less  labor  than  when  stirring  is  delayed 
until  all  whey  has  been  removed.  If  the  curd  is 
not  properly  firmed,  vigorous  hand-stirring  may 
cause  serious  loss  of  fat  here.  Too  much  free  whey 
should  not  be  left  around  or  in  the  pieces  of  curd 
at  this,  time,  as  it  enables  lactic  acid  to  develop  too 
fast,  owing  to  the  presence  of  the  milk-sugar  in  the 
whey  (p.  45)- 

CHEDDARING  THE  CURD 

This  operation  is  the  main  distinctive  feature  of 
the  cheddar  method  of  cheese-making.  It  consists 
essentially  of  two  operations  or  a  continuation  of 
one  operation  in  two  stages :  ( I )  Piling  or  matting 
of  curd  and  (2)  cutting  curd  into  strips  and  con- 
tinuing the  operation  of  piling  and  repiling. 

Piling  or  matting  curd. — As  soon  as  the  curd  has 
been  stirred  enough  to  become  sufficiently  dry,  it 


CUTTING    CURD    TO    SALTING  33 

should  be  piled  evenly  along  the  two  sides  of  the 
vat,  with  an  open  channel  4  to  6  inches  wide  be- 
tween the  piles,  to  facilitate  the  ready  drainage  of 
the  whey  that  comes  from  the  curd.  The  vat  should 
have  dip  enough  to  enable  the  escaping  whey  to 
pass  away  rapidly  and  keep  it  from  lying  in  pools 
around  the  curd.  Up  to  this  time  the  curd  should 
not  have  been  allowed  to  become  lumpy,  but,  as 
far  as  possible,  the  small  pieces  should  be  kept 
separated.  This  results  in  a  more  uniform  expul- 
sion of  whey,  a  more  uniform  development  of  acid 
and  a  more  uniform  color  in  the  curd.  Some 
cheese-makers  use  curd-sinks  to  dry  the  curd  in 
during  this  stage.  Others  use  strainer-racks  on  the 
bottom  of  the  vats.  In  using  these,  the  curd  and 
whey  are  dipped  in  pails  on  to  the  racks,  which  are 
covered  with  cheese-cloth.  The  whey  drains 
through  the  racks  and  the  curd  is  easy  to  stir.  The 
curd-sinks  and  vat-racks  are  of  some  aid  in  han- 
dling curd  from  overripe  milk,  but  under  normal 
conditions  they  have  no  particular  advantage  over 
the  vat. 

Cutting  and  repiling  curd. — As  soon  as  the  curd 
has  become  matted  together  sufficiently,  forming 
a  solid  mass  about  6  inches  deep,  it  should  be  cut 
into  blocks  or  strips  6  to  8  inches  wide  and  turned 
over,  the  top  going  on  the  bottom.  This  takes  15 
to  20  minutes  from  the  time  of  piling.  If  the  curd 
contains  excessive  amounts  of  visible  or  free  whey, 
the  blocks  should  be  cut  very  narrow  and  turned 
as  soon  as  matted.  After  draining  about  15  min- 
utes, the  strips  are  piled  in  layers  two  deep,  each 
time  the  upper  part  being  turned  down.  The  blocks 


34        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

are  then  turned  every  15  minutes  until  the  opera- 
tion is  completed.  After  a  while  the  strips  may  be 
piled  in  deeper  layers.  The  repiling  is  performed 
again  and  again,  always  exposing  to  the  air  the 
portions  that  were  turned  inside  on  the  previous 
piling,  in  order  to  keep  the  temperature  uniform 
through  the  mass.  The  operation  is  hastened  by 
piling  the  strips  two  or  three  layers  deep.  If  the 
curd  is  very  moist  and  the  formation  of  acid  goes 
on  quickly,  it  is  not  advisable  to  pile  the  blocks  in 
deep  layers.  It  is  better  to  separate  them  so  that 
they  will  dry  out  as  soon  as  possible. 

Object  of  cheddaring  operation. — The  object  of 
the  cheddaring  operation  is  to  accomplish  two  re- 
sults: (i)  The  formation  of  a  curd  containing  less 
water  by,  the  removal  of  whey;  and  (2)  the  forma- 
tion of  a  characteristic  body  and  texture  in  the 
curd.  The  physical  condition  of  the  curd  changes 
from  a  tough,  rubber-like  consistency  with  a  high 
water  content  to  a  mass  having  a  smooth,  velvety 
appearance  and  feeling,  and  a  softer,  somewhat 
plastic  consistency.  The  texture  also  changes  so 
that  the  curd  acquires  a  peculiar  fibrous  condition 
or  grain,  tearing  off  somewhat  like  the  cooked 
meat  of  a  chicken's  breast.  Along  with  these 
changes  the  curd  forms  longer  strings  on  a  hot 
iron,  usually  an  inch  or  more  after  the  cheddaring 
has  continued  for  some  time.  Some  chemical 
changes  appear  to  take  place  in  the  proteins.  The 
changes  noted  above  are  due  to  the  formation  of  a 
substance  in  the  curd  which  is  dissolved  in  warm, 
5  per  cent  brine  (p.  147).  This  substance  in  pure 


CUTTING    CURD    TO    SALTING  35 

condition     forms     very     long     strings     when     warm. 
(Figs.  32  and  33,  p.  148.) 
Completion     of     the    cheddaring     process. — The 

cheddaring  process  is  regarded  as  complete  when 
we  have  the  following  conditions:  (i)  The  curd 
forms  strings  on  a  hot  iron  an  inch  to  an  inch  and 
a  half  in  length.  (2)  The  whey  running  from  the 
curd  shows  an  acidity  of  0.65  to  0.90  per  cent,  de- 
pending on  the  whey  content  of  the  curd  and  the 
manner  in  which  it  is  cheddared.  (3)  The  curd 
should  be  velvety  in  appearance  and  feeling,  and  tear 
apart  like  the  breast-meat  of  a  chicken. 

MILLING  CURD 

When  the  cheddaring  process  is  complete,  as 
determined  by  the  tests  given,  the  curd  is  ready  to 
mill.  The  objects  of  milling  are  to  cut  the  curd 
into  small  pieces  of  uniform  size,  in  order  that  the 
curd  may  be  salted  more  evenly  and  handled  more 
easily  in  salting  during  the  rest  of  the  cheese- 
making  process;  and  also  to  permit  the  escape  of 
more  whey.  In  cheddaring  the  curd,  it  should  be 
piled  so  that,  when  ready,  the  strips  will  be  in 
convenient  shape  and  size  for  milling.  The  mill 
should  cut  the  curd  into  small  pieces  of  uniform 
size,  and  should  do  it  without  crushing  or  squeez- 
ing the  milk-fat  from  the  curd.  If  a  steam-power 
curd-mill  is  used,  it  should  not  be  run  too  rapidly, 
for  it  will  cut  the  curd  unevenly  and  the  texture 
of  the  cheese  will  be  poor.  After  milling,  the  pieces 
of  curd  should  be  well  stirred,  kept  apart,  and  freely 
exposed  to  fresh  air.  At  this  stage  the  freshly  cut 
surfaces  afford  an  excellent  channel  for  the  escape 


36       SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

of  gases  and  undesirable  flavors.  The  airing  and 
stirring  are  made  easy  by  the  use  of  forks. 

After  milling,  the  curd  is  piled  up  in  order  to 
flatten  out  pin-holes,  if  any,  and  stirred  enough  to 
keep  it  from  matting  together.  The  softening  of 
the  curd  continues  after  milling,  along  with  the  fur- 
ther formation  of  lactic  acid.  The  curd  should  be 
kept  warm  all  the  time. 

If  the  operations  up  to  this  time  have  been  prop- 
erly managed,  the  whey  remaining  in  the  curd  has 
become  a  part  of  it  to  such  an  extent  that  not  a 
drop  can  be  squeezed  by  pressure  of  the  curd  in 
the  hand.  If,  however,  the  whey  has  not  become 
perfectly  incorporated  with  the  curd-solids,  more  or 
less  free  or  unassimilated  whey  is  found  inside  the 
original,  small  pieces  of  curd;  and,  when  these  are 
broken  in  the  milling,  white  whey  runs  out  of  the 
curd,  involving  considerable  loss  of  fat. 


CHAPTER  IV 

Operations  from  Salting  Curd  to  Removal 
from  Press 

SALTING  CURD 

When  to  apply  salt. — After  the  pieces  of  curd 
have  become  well  contracted  and  feel  silky  and 
mellow,  they  are  ready  to  be  salted.  The  curd  at 
this  stage  should  show  by  the  hot-iron  test  strings 
iy2  inches  long,  but  this  test  cannot  be  relied  upon, 
as  most  curds  become  more  or  less  greasy  after  mill- 
ing, and  do  not  so  easily  stick  to  a  hot  surface.  A 
test  of  the  whey  exuding  from  the  curd  is  much 
more  reliable.  It  should  have  0.90  to  1.2  per  cent 
of  acidity,  as  shown  by  the  acid  test.  This  is  the 
most  reliable  test  for  indicating  when  curd  is  ready 
for  salting,  and  it  is  equally  useful  at  other  stages; 
but  students  and  cheese-makers  should  be  familiar 
with  the  use  of  all  tests. 

It  is  often  a  difficult  matter  to  tell  just  when  a 
curd  is  in  the  best  condition  for  salting,  and  this 
knowledge  comes  only  as  the  result  of  long  expe- 
rience. Generally,  the  curd  smells  like  toasted  cheese 
when  rubbed  on  a  hot  iron;  and,  when  squeezed  be- 
tween the  hands,  a  certain  amount  of  fat  may  start, 
but  these  tests  are  not  reliable.  The  per  cent  of 
acidity  allowed  to  develop  before  salting  depends 
on  the  condition  of  the  curd  and  also  the  conditions 
of  temperature  and  moisture  under  which  the  cheese 

87 


38       SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


is  to  be  stored  and  ripened.  If  the  cheese  is  to  be 
kept  for  any  length  of  time  in  a  warm  room,  the  de- 
velopment of  acidity  should  be  greater  and  the  curd 
matured  more.  This  is  especially  true  if  the  curd 
is  gassy  or  weak-bodied.  If  the  curd  is  free  from 
gas,  and  the  cheese  is  to  be  kept  in  cold  storage  till 
ready  for  consumption,  the  acidity  need  not  be  so 
great ;  but,  in  any  case,  it  should  be  sufficient  to  insure 
a  mellow  body  in  the  cheese. 

Amount  and  kind  of  salt  to  use. — The  amount  of 
salt  used  depends  on  (i)  the  amount  of  whey  in  the 
curd,  (2)  its  acidity,  and  (3)  the  type  of  cheese 
desired.  For  ordinary  factory  milk,  from  1^2  to  2.^/2 
pounds  of  salt  for  1,000  pounds  of  milk  used  will 
be  sufficient,  but  in  extreme  cases  these  limits 
may  be  exceeded.  A  moist  curd  is  usually  salted 
more.  The  weight  of  milk,  however,  is  not  an  ac- 
curate basis  for  determining  the  amount  of  salt  to 
use.  It  is  much  better  to  use  the  weight  of  curd 
or  the  percentage  of  fat  in  milk  as  indicated  below. 
Assuming  that  curd  ready  for  salting  ,  contains 


Per  cent  of 
fat  in  milk 

From  1  ,000  pounds  of  milk 
Pounds  of  milled  curd  con- 
taining 40  per  cent  of  water 

Amount  of  salt  to  use 
Lbs.    Ozs. 

3.0 

87.4 

1      12 

3.1 

89.8 

1      13* 

3.2 

92.2 

1      15 

3.3 

94.6 

2         i 

3.4 

97.0 

2       2 

3.5 

99.4 

2       3* 

3.6 

101.8 

2       5 

3.7 

104.2 

2       6* 

3.8 

106.6 

2       8 

3.9 

109.0 

2       9* 

4.0 

111.4 

2     11 

4.1 

113.8 

2      12* 

4.2 

116.2 

2      14 

4.3 

118.6 

2     15* 

4.4 

121.0 

3       2 

4.5 

123.4 

3       3* 

SALTING    TO    TAKING    FROM     PRESS  39 

about  40  per  cent  of  water,  1,000  pounds  of  milk 
would  furnish  about  the  amounts  of  curd  for  the  dif- 
ferent percentages  of  fat  in  milk  shown  on  page  38. 

Salt  of  fairly  coarse  grain  is  preferable,  because 
it  dissolves  more  slowly  and  penetrates  the  curd 
more  thoroughly.  Special  brands  of  cheese  salt  are 
prepared  by  manufacturers  and  are  generally  shipped 
in  paper-lined  barrels. 

How  to  apply  salt. — The  curd  should  be  spread 
out  thinly  over  the  bottom  of  the  vat,  and,  if  neces- 
sary, cooled  to  90°  F.  Both  curd  and  salt  should 
be  free  from  lumps.  The  salt  should  be  put  on  in 
at  least  three  applications,  and  each  time  should 
be  evenly  distributed  over  the  surface.  After  each 
sprinkling  of  salt,  the  curd  should  be  well  stirred 
with  forks.  Applying  salt  too  rapidly  or  all  at  once 
hardens  the  outside  of  the  small  pieces  of  curd  and 
hinders  its  absorption.  A  fine  hair  or  copper  sieve 
is  of  considerable  aid  in  regulating  the  application 
of  salt.  Salt  in  cheese  affects  flavor,  body,  texture 
and  keeping  quality  (p.  343). 

Effects  of  salting. — While  salt  is  added  mainly 
for  the  sake  of  the  taste  it  gives  to  cheese,  it  pro- 
duces other  effects,  such  as  (i)  aiding  in  removal  of 
whey;  (2)  hardening  and  contracting  the  curd; 
(3)  checking  or  retarding  the  formation  of  lactic 
acid;  and  (4)  checking  undesirable  forms  of  fer- 
mentation. An  unsalted  cheese  cures  more  rapidly 
and  is  apt  to  develop  a  bitter  flavor,  the  intensity 
increasing  with  increase  of  ripening  temperature. 
Excessive  salting  makes  a  cheese  mealy,  because 
too  dry,  and  it  cures  slowly.  Much  of  the  salt 
added  passes  into  the  whey.  Green  cheese  normally 


4O        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

salted  contains  0.6  to  I  per  cent  of  salt,  and  this 
increases  somewhat  in  'the  ripened  cheese,  through 
loss  of  moisture  (p.  344). 

An  increased  quantity  of  salt  is  of  advantage  in 
correcting  such  defects  as  gassy,  highly  acid,  or  very 
soft  cheese.  Excessive  loss  of  fat  may  often  be 
avoided  by  the  early  addition  of  salt,  which  hardens 
the  surface  of  the  pieces  of  curd  and  prevents  further 
exudation  of  fat. 

PRESSING  CURD  AND  DRESSING  CHEESE 

Condition  and  temperature  of  curd  when  ready 
for  press. — Before  the  curd  is  placed  in  the  hoops, 
the  salt  should  be  completely  dissolved;  the  curd 
should  feel  mellow  and  silky.  No  fixed  pressing 
temperature  can  be  prescribed  even  for  normal 
curd,  since  there  are  several  variable  factors  which 
we  must  take  into  consideration.  We  can  say  that, 
in  general,  under  ordinary,  normal  conditions,  the 
temperature  should  be  not  much  above  80°  F.,  with 
a  range  of  variation  from  78°  to  85°  F.,  according  to 
certain  conditions,  among  the  most  important  of 
which  are  the  following:  (i)  Size  of  cheese  made; 
(2)  temperature  of  room;  (3)  condition  of  curd; 
and  (4)  rate  at  which  pressure  is  applied.  Small- 
sized  cheese,  such  as  Young  Americas,  Prints  and 
Picnics,  should  be  put  in  press  warmer  than  larger- 
sized  cheese,  since  they  cool  more  rapidly.  During 
early  spring,  late  fall,  and  winter  months,  the  press- 
ing temperature  should  be  higher  than  during  the 
summer  months.  During  the  hot  weather  of  sum- 
mer, it  may  be  necessary  to  cool  the  nird  before 


SALTING  AND  TAKING   FROM   PRESS  4! 

pressing,  which  can  be  done  by  running  cold  water 
around  the  outside  of  the  vat,  or  by  placing  the  curd 
•in  a  cold  room  for  a  short  time.  One  can  usually 
allow  a  somewhat  wider  range  in  the  pressing  tem- 
perature when  handling  a  normal  curd  than  in  the 
case  of  one  which  is  noticeably  defective,  such  as  a 
greasy  or  a  harsh  curd.  The  faster  a  curd  is  put 
into  the  hoop  and  pressed,  the  lower  the  temperature 
it  may  be  permitted  to  have. 

The  effects  of  pressing  at  too  high  a  temperature 
are  the  following:  (i)  Excessive  loss  of  fat  and 
consequent  loss  of  yield;  (2)  the  pieces  of  curd  be- 
come greasy  on  the  outside  and  do  not  stick  to- 
gether perfectly,  which  results  in  producing  cheese 
of  less  close  texture  on  account  of  the  increased 
number  and  size  of  the  mechanical-holes;  (3)  greasy 
curd  prevents  bandage  sticking  to  cheese;  (4)  high 
temperature  favors  development  of  gas  and  conse- 
quent huffing;  (5)  the  loss  of  fat  has  the  same 
effect  as  skimming  milk,  as  it  makes  the  cheese  too 
dry. 

The  effects  of  pressing  at  too  low  temperature  are 
the  following:  (i)  The  pieces  of  curd  do  not  stick 
together  perfectly,  resulting  in  cheese  of  open  texture 
and  imperfect  rind  formation,  which  affords  an  op- 
portunity for  entrance  of  mold  and  skippers;  (2)  it 
may  sometimes  cause  a  mottled  appearance  when  a 
sample  is  drawn  by  a  cheese-trier;  (3)  the  cheese 
retains  more  whey. 

Object  of  pressing  curd. — The  object  of  pressing 
curd  is  to  give  the  cheese  a  convenient  form  for 
handling  and  a  definite,  characteristic  shape  for 
market,  and  not  alone  to  squeeze  out  whey,  which 


42        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

should  be  removed  mostly  while  the  curd  is  in  the 
vat.  Pressing  will  not  make  a  close-textured  cheese, 
if  the  curd  is  gassy  or  too  sweet.  If  the  cheese  is 
to  be  close  in  texture,  the  curd  must  be  full  matured 
before  salting. 

Preparing  hoop  for  receiving  curd. — A  round  cot- 
ton cap-cloth  of  the  size  of  the  hoop  is  wrung  out 
of  hot  water  and  placed  in  the  bottom  of  the  hoop. 
The  bandage  is  then  placed  in  the  hoop,  with 
the  edge  turned  in  evenly  about  one  inch  on 
the  bottom.  The  curd  is  weighed  in  order  to  in- 
sure a  uniform  size  of  cheese  and  is  then  put  into 
the  hoop.  The  hoops  should  not  be  filled  too  full, 
since  the  curd  will  be  squeezed  out  around  the  top 
when  pressed.  A  cotton  cap-cloth  is  then  placed 
over  the  top  of  the  curd,  and  then  the  ring  and 
follower.  Steel  rings  and  followers  are  preferable 
to  fibrous  rings  and  wooden  followers.  They  are 
more  sanitary,  easier  to  clean,  are  not  absorbent,  and 
do  not  contract  or  expand  easily. 

Applying  pressure. — When  the  curd  is  put  in 
press  in  normal  condition,  a  moderate  pressure  will 
cause  the  pieces  of  curd  to  cement  together  in  a 
smooth,  solid  mass.  The  pressure  should  be  uni- 
form and  continuous  for  24  hours.  With  a  screw- 
press,  the  pressure  is  applied  lightly  and  gradually 
at  first,  full  pressure  being  reached  in  about  15 
minutes,  and  the  press  is  tightened  as  fast  as  the 
screws  become  loose,  especially  during  the  first 
hour.  After  the  curd  has  been  in  the  press  45  to  60 
minutes,  it  should  be  firmly  cemented  and  ready  for 
dressing. 


SALTING    TO    TAKING    FROM     PRESS  43 

Dressing  cheese. — Too  much  care  cannot  be  taken 
in  finishing  a  cheese  for  market.  The  appearance 
greatly  influences  an  intending  purchaser.  As  soon 
as  the  cheese  is  sufficiently  pressed,  it  is  taken  from 
the  hoop  and  placed  on  a  dressing-bench.  The 
bandage  is  pulled  up,  made  free  from  wrinkles,  and 
trimmed  to  about  one  inch  on  each  end  with  a  sharp 
knife.  A  starched  cap-cloth  is  placed  on  each  end, 
outside  the  bandage.  Over  these,  the  cotton  cloths 
are  placed,  and  the  cheese  is  then  returned  to  the 
hoop,  where  it  is  left  until  the  following  morning. 
The  cheese  should  then  be  taken  from  the  press 
and  examined  for  imperfections  in  finish;  if  any  are 
present,  they  should  be  remedied  and  the  cheese 
then  returned  to  the  press  until  the  hoops  are  re- 
quired for  use  again.  It  is  better  to  have  the  cheese 
in  the  hoops  under  pressure  for  48  hours  than  for 
only  24. 

Plenty  of  hot  water  and  clean,  soft  press-cloths 
should  be  used  to  insure  a  good  rind  on  the  cheese. 
Some  cheese-makers  place  a  cotton  cloth  around 
the  entire  side  of  the  cheese.  This  improves  the 
rind  and  protects  the  surface  from  any  dirt  or  rust 
marks  that  may  be  on  the  hoops.  Others  do  not 
take  the  cheese  from  the'  hoops  to  dress  them,  but 
place  a  starched  cap-cloth  in  the  hoop  before  adding 
the  curd.  Then,  in  dressing,  the  bandage  is  pulled 
up  from  the  top  and,  after  being  trimmed,  a  starched 
cloth  is  placed  on  the  upper  end.  This  method 
causes  a  greater  waste  of  bandage,  but  otherwise 
is  satisfactory.  The  mechanical  manipulations  in- 
volved in  preparing  the  hoops  and  dressing  the 
cheese  can  be  properly  learned  only  from,  actual 
practice. 


44       SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


SIZES    OR   STYLES   OF   AMERICAN    CHED- 
DAR CHEESE 

American  cheddar  cheese  has  come  to  be  put  upon 
the  market  in  an  increasing  number  of  varieties  or 
styles  in  respect  to  size.  The  main  difference  in 
most  cases  is  simply  one  of  shape  or  size.  The  fol- 
lowing list  includes  the  most  common  varieties  that 
appear  in  trade: 


Name 

Shape 

Approximate 
Size 

Approximate 
Weight 

In.  diam. 

Pounds 

1.  Cheddar  or  Export 

Cylindrical 

14-15 

60-70 

2.  Flats  or  twins 

14-15 

30-35- 

3.  Home-trade 

11-13 

20-25 

4.  Daisies 

12-13 

20 

5.  Young  America 

7-8 

g-12 

6.  Longhorn 
7.  Picnic 

5 
4-5 

12 
1-2 

8.  Square 
9.   Print 

Rectangular 

Various  sizes 
10  x  10x2$ 

(3-4  in.  thick) 
10  (marked  in  blocks 

or  prints) 

CHAPTER  V 

Moisture  and  Acidity  in  Curd  and  Cheese : 
Conditions,  Effects  and  Control 

The  detailed  operations  of  cheese-making  have 
for  their  primary  object,  in  large  measure,  regula- 
tion of  the  amount  of  water  and  degree  of  acidity 
in  the  curd.  So  important  is  the  control  of  these 
factors  in  relation  to  the  quality  of  cheese,  that 
sometimes,  under  abnormal  conditions,  as,  for  ex- 
ample, in  case  of  overripe  milk,  they  can  be  regu- 
lated only  by  sacrifice  of  some  of  the  fat,  and  the 
question  of  saving  fat  then  becomes  a  matter  of 
secondary  importance.  Of  such  importance  is  a 
knowledge  of  these  factors  and  their  relations  to  the 
detailed  operations  of  cheese-making  that  a  special 
chapter  seems  desirable,  even  though  the  treatment 
involves  some  repetitions. 

To  a  considerable  extent,  moisture  and  acidity 
are  closely  associated.  Water  means  whey,  of 
course,  and  the  most  important  constituent  of  whey 
is  milk-sugar,  the  raw  material  used  in  making 
lactic  acid.  The  larger  the  percentage  of  water 
or  whey  in  curd  or  fresh  cheese,  the  larger  is  the 
amount  of  milk-sugar,  and,  therefore,  the  greater  is 
the  degree  of  acidity  that  can  be  developed.  The 
relations  of  moisture  can  be  better  understood  if 
we  keep  in  mind  the  connection  between  (i) 
moisture,  (2)  whey,  (3)  milk-sugar  and  (4)  acidity. 

45 


46         SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

CAUSES  OF  EXCESSIVE  MOISTURE 

Among-  the  most  common  causes  of  excessive 
water  in  curd  and  cheese  are  the  following :  ( I ) 
Cutting  curd  coarse  or  when  too  hard;  (2)  insuffi- 
cient heating  of  curd  in  whey;  (3)  heating  too 
rapidly,  thus  hardening  the  outside  of  the  pieces 
of  curd  and  preventing  escape  of  whey;  (4)  low 
degree  of  acidity  before  removing  whey,  usually 
associated  with,  or  caused  by,  insufficient  heating; 

(5)  allowing  curd  to  lie  in   whey  too  long  and   re- 
absorb  whey;    (6)    insufficient  stirring  of  curd  after 
removal    or    partial    removal    of    whey;     (7)     high 
piling  of  curd;   (8)   prolonged  maturing  in  cheddar- 
ing  operation   and   postponement  of   milling   in   case 
of  soft  curd;    (9)    insufficient  amount  of  salt;    (10) 
soaking  curd  in  water  previous  to  salting  (p.  57). 

CAUSES  OF  INSUFFICIENT  MOISTURE 

The  following  are  common  causes  of  insufficient 
moisture  in  curd:  (i)  Cutting  curd  very  fine;  (2) 
heating  curd  too.  long  or  at  too  high  a  tempera- 
ture; (3)  excessive  stirring  of  curd  when  the  whey 
is  removed;  (4)  too  much  salt;  (5)  excessive  loss 
of  fat  may  cause  curd  or  cheese  to  appear  too  dry; 

(6)  high  temperature  and  low  humidity  in  curing- 
room. 

EFFECTS   OF   EXCESSIVE   AND    OF   DEFI- 
CIENT MOISTURE 

Among  the  more  prominent  effects  to  be  noticed 
in  relation  to  water  in  cheese-curd  and  cheese,  we 


MOISTURE   AND   ACIDITY    IN    CURD,    ETC.  4/ 

mention  the  following:  (i)  Development  of  acid- 
ity; (2)  influence  on  body;  (3)  relation  to  texture; 
(4)  effect  on  flavor;  (5)  influence  on  keeping  qual- 
ity; and  (6)  relation  to  finish. 

Moisture  and  acidity. — The  introduction  to  this 
chapter  gives  the  cause  for  the  close  relation  of 
moisture  in  curd  to  the  formation  of  acid.  In 
case  of  a  wet  curd,  characterized  by  much  water 
(whey),  we  have  a  greater  amount  of  milk-sugar 
ready  to  form  an  additional  amount  of  acid;  and,  if 
the  temperature  and  other  conditions  are  favor- 
able, acidity  increases  rapidly.  In  the  case  of  a 
dry  curd,  the  acidity  increases  more  slowly,  because 
there  is  less  whey,  which  means  less  milk-sugar  with 
which  to  make  acid. 

Moisture  and  body. — Curd  containing  too  much 
moisture  (whey)  becomes  soft  and  produces  a  soft, 
weak-bodied  cheese  (p.  87),  which  in  extreme 
cases  is  sticky  and  pasty  (p.  63).  The  soaking  of 
curd  in  water  after  milling  causes  the  absorption 
of  5  per  cent  of  water,  more  or  less,  and  usually 
results  in  a  poor  body.  Cheese  containing  too  little 
moisture  becomes  dry,  mealy,  crumbly,  more  or 
less  rubbery,  tough  and  hard.  Such  cheese  is  in 
no  way  attractive.  When  curd  is  too  dry,  the 
maturing  process  takes  place  with  some  degree 
of  difficulty  and  the  curd  is  slow  to  change  into 
the  characteristic,  mellow,  smooth,  meaty  body  that 
is  desired.  This  is  due  to  the  presence  of  too  little 
whey  in  the  curd,  that  is,  too  little  milk-sugar  with 
which  to  form  acid. 

Moisture  and  texture. — Excessive  whey  in  curd 
and  cheese  is  apt  to  favor  the  production  of  holes, 


48      SCIENCE     AND     PRACTICE     OF     CHEESE-MAKING 

especially  when  exposed  to  high  temperatures. 
Under  the  combined  conditions  of  such  defects  of 
texture  and  the  soft,  pasty  body  characteristic  of 
such  cheese,  the  cheese  easily  loses  its  shape,  bul- 
ging more  or  less ;  this  sometimes  goes  so  far  as  to 
cause  the  cheese  to  roll  off  the  shelf. 

Moisture  and  flavor. — Cheese  made  from  curd 
containing  a  large  percentage  of  water  (whey)  is 
apt  to  develop  offensive  flavors  in  ripening,  espe- 
cially when  kept  at  temperatures  above  65°  F.  In 
some  cases,  excessive  moisture  results  in  sour  or 
acid  cheese.  Dry  cheese  develops  flavor  slowly 
and  can  stand  a  higher  ripening  temperature. 

Moisture  and  keeping  quality. — Cheese  contain- 
ing a  large  amount  of  moisture  has  poor  keeping 
quality,  as  already  indicated  above  in  connection  with 
flavor  and  texture,  while  the  reverse  is  true  of 
dry  cheese. 

Moisture  and  finish. — Cheese  containing  too 
much  moisture  loses  its  shape  easily  in  hot 
weather,  when  the  temperature  of  the  curing- 
room  can  not  be  controlled.  In  such  cheese,  the 
rind  formation  is  usually  poor  and  cap-cloths  do  not 
stick  well. 

CONTROL  OF  MOISTURE  IN  CHEESE- 
MAKING 

We  now  give  briefly  the  means  to  be  used  in 
controlling  moisture  at  different  stages  of  cheese- 
making. 

(i)  Cutting  curd. — The  finer  the  pieces  into 
which  the  curd  is  cut,  the  more  easily  does  the 


MOISTURE    AND    ACIDITY    IN    CURD,    ETC.  49 

whey  escape ;  the  larger  the  pieces  of  curd,  the 
less  rapid  the  escape  of  whey.  Under  the  same 
conditions  of  treatment,  a  coarse-cut  curd  retains 
more  whey  than  one  fine-cut.  When  curd  is  cut 
before  it  becomes  hard  the  whey  escapes  more 
easily  than  in  the  case  of  curd  cut  after  it  becomes 
hard. 

(2)  Heating    curd    in    whey. — When    the    tem- 
perature of  curd  in  whey  is  raised  too   rapidly,  the 
film   on  the  outside  of  the  pieces  of  curd  is  harder 
and    more     impervious,     which     seriously    interferes 
with   the   escape   of    whey.        If   the   temperature    is 
not    raised    sufficiently     high,    the     whey    does    not 
escape  as  completely  as  it  should;    this  is  especially 
the    case    when    an    insufficient    degree   of    acidity    is 
developed.       Therefore  the  curd  in  the  whey  should 
be    heated    gradually    (p.    30)    and    the    temperature 
raised  to  the  degree  called  for  by  the  existing  con- 
ditions   (p.  29).     For   method  of  avoiding  dry  curd 
see  p.   121. 

(3)  Removal     of     whey. — The    whey    should    be 
removed  promptly  when  the  curd  is  properly  firmed. 
When    allowed    to    lie    in    whey    after    reaching    the 
right  condition,  the  curd  may  reabsorb  whey,  which 
can    be    removed   only    with    extreme    difficulty    and 
usually   with   considerable   loss   of   fat 

(4)  Stirring  of  curd. — Curd  should  be  freed  from 
whey   and   made    properly    dry    by    sufficient    stirring 
after  removal  of  whey   (p.  32). 

(5)  Cheddaring    curd. — In  case  of  wet  curd,   it 
should    not   be    piled    too    high    in   the    operation    of 
cheddaring,    since   this    results    in    retention   of   more 
whey    than    when    curd    is    cut    fine    and    not    piled 


50        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

at  all.     in   the   case   of   dry  curds,   pile   higher,  etc., 
(p.   121). 

(6)  Milling  curd.  —  Early  milling  of  curd  favors 
the  escape   of   whey  and  may  be   resorted   to   when 
too   much    whey   is   present   at   this    stage,    especially 
in  the  case  of  a  soft  curd.     Dry  curds  should  not  be 
milled  early. 

(7)  Salting      curd.  —  The    amount    of    whey     in 
cheese    can    be    controlled,    to    some    extent,    by    the 
amount  of  salt  used.     In  case  of  excessive  moisture 
in  curd  at  the  time  of  salting,  this  may  be  reduced 
by  using  an  increased  amount  of  salt.     In  case  of  a 
dry  curd,  less  salt  should  be  used  (p.  121). 

(8)  Ripening    process.  —  The    amount    of    mois- 
ture   in    cheese    can    be    regulated   to    a    considerable 
extent   by    control   of   temperature   and    humidity    in 
the  curing-room   (p.  317).       Covering  cheese  with  a 
layer  of  paraffin  goes  far  in  retaining  water  in  cheese 
(P- 


CAUSES  OF  EXCESSIVE  ACIDITY 

Among  the  common  causes  of  excessive  acidity 
in  curd  and  cheese  are  the  following:  (i)  Taking 
too  much  overripe  milk  from  patrons;  (2)  ripen- 
ing milk  too  much  in  vat  before  adding  rennet; 
(3)  use  of  too  much  starter;  (4)  too  long  contact 
of  curd  with  whey  or  too  high  temperature;  (5) 
any  condition  which  favors  the  retention  of  too  much 
whey  in  curd  and  cheese  (p.  116). 

CAUSES  OF  INSUFFICIENT  ACIDITY 

The  following  are  common  causes  of  too  low  a 
degree  of  acidity;  (i)  Insufficient  ripening  of 


MOISTURE   AND   ACIDITY    IN    CURD,    ETC.  51 

milk  before  adding  rennet;  (2)  low  degree  of  tem- 
perature in  heating  curd  in  whey;  (3)  removal  of 
whey  too  soon;  (4)  any  condition  that  favors  the 
rapid  removal  of  whey  and  the  formation  of  an 
excessively  dry  curd  (p.  121). 

EFFECTS  OF  EXCESSIVE  AND  DEFICIENT 
ACIDITY 

Among  the  more  prominent  effects  to  be  no- 
ticed in  relation  to  acidity  in  curd  and  cheese,  we 
mention  the  following:  (i)  Influence  on  rennet 
action;  (2)  relation  to  shrinking  of  curd;  (3)  ef- 
fect on  expulsion  of  whey;  (4)  influence  on  color 
of  cheese;  (5)  relation  to  body  of  cheese;  (6)  ef- 
fect on  texture  of  cheese;  (7)  influence  on  flavor 
of  cheese;  (8)  relation  to  keeping  quality  of 
cheese;  and  (9)  effect  on  finish  or  general  appear- 
ance. 

Acidity  and  rennet  action. — At  the  temperature 
used  in  cheese-making,  rennet -extract  coagulates 
milk-casein  only  when  acids  or  acid  salts  are  pres- 
ent (p.  306).  The  greater  the  percentage  of  acidity, 
up  to  certain  limits,  the  more  rapid  is  rennet 
coagulation,  other  conditions  being  uniform  (p. 

307)- 

Acidity  and  contraction  of  curd. — The  greater 
the  acidity  of  milk,  the  more  rapid  is  the  contrac- 
tion of  the  curd,  other  conditions  being  uniform. 
This  is  not  the  same  as  saying  that  the  contraction 
is  caused  by  acidity;  acidity  is  probably  one  of  two 
or  more  causes,  or  it  may  be  simply  a  necessary 
condition  for  the  continued  action  of  rennet,  tem- 
perature being  another  important  condition  for  the 


52        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

shrinking  of  curd.  The  knowledge  of  the  relation 
of  acidity  and  temperature  to  contraction  of  curd 
enables  the  cheese-maker  to  heat  the  curd  in  the 
whey  more  rapidly,  since,  in  the  case  of  excessive 
acidity  at  the  start,  he  can  increase  with  comparative 
rapidity  the  temperature,  without  danger  of  harden- 
ing the  external  film  of  the  small  pieces  of  curd  and 
so  preventing  further  expulsion  of  whey. 

Acidity  and  expulsion  of  whey. — The  contrac- 
tion of  curd  is  closely  associated  with  expulsion  of 
whey  and  the  relation  of  acidity  to  the  two  actions 
is  practically  the  same. 

Acidity  and  color  of  cheese. — Formation  of  too 
great  a  degree  of  acidity  bleaches  the  color  in  the 
curd,  making  it  pale  when  the  action  is  even,  and 
mottled  when  the  acidity  is  different  in  different 
portions.  This  condition  is  generally  caused  by  the 
retention  of  too  much  milk-sugar  (whey)  in  curd 
and  cheese. 

Acidity  and  body  of  cheese. — Excessive  acidity 
produces  imperfect  body  in  cheese,  making  it 
harsh,  corky  and  mealy.  A  certain  degree  of  acidity 
is  an  essential  condition,  if  not  one  of  the  causes, 
of  the  formation  of  a  smooth,  firm,  silky  body. 
Insufficient  acidity  may  cause  cheese  to  be  weak- 
bodied. 

Acidity  and  texture. — Cheese  made  from  curd 
containing  a  small  amount  of  acidity  is  often  faulty 
in  texture.  Among  such  defects  are  holes,  usually 
called  "sweet  holes."  Excessive  acidity  and  cracks  in 
cheese  are  often  associated. 

Acidity  and  flavor. — The  characteristic  flavor  of 
cheddar  cheese  is  not  developed  without  a  certain 


MOISTURE   AND   ACIDITY    IN  .CURD,    ETC.  53 

degree  of  acidity.  Excessive  acidity  (whey)  gives 
the  cheese  a  sour  flavor.  Insufficient  acidity  is  apt 
to  be  accompanied  by.  a  sickish  flavor,  unless  the 
cheese  is  ripened  with  care  at  sufficiently  low  tem- 
perature. 

Acidity  and  keeping  quality. — It  has  been  al- 
ready stated  (p.  18)  that  the  presence  of  lactic 
acid  bacteria  in  milk  and  curd  is  essential  to  pre- 
vent the  development  of  undesirable  forms  of 
fermentation,  which  may  be  present  in  the  early 
stages  of  cheese-making.  The  lactic  acid  thus 
formed  is  the  active  material  employed  in  doing  this 
sanitary  work.  Cheese  with  too  little  acidity  usually 
becomes  defective  in  flavor  in  a  comparatively  short 
time. 

Acidity  and  finish. — Excessive  acidity  (whey) 
causes  formation  of  poor  rind;  frequently  the  rind 
cracks  and  leaks  whey. 

• 

CONTROL    OF    ACIDITY    IN    CHEESE- 
MAKING 

Below  we  give  in  brief  form  the  means  to  be  used 
in  controlling  acidity  in  the  operations  of  cheese- 
making. 

(1)  Producer's    care    of   milk. — In   order  to   re- 
tard   the    too    rapid    growth    of    lactic    acid    bacteria 
before   milk   is    delivered   at   the    cheese-factory,    the 
milk  should  be  cooled  at  once  after  milking  to  60° 
F.,  or  better  to  50°  F.,  and  not  allowed  to  get  above 
this  temperature. 

(2)  Ripening      milk. — In      making      sweet-curd 
cheese,   care   must   be    taken    not    to    ripen    the    milk 


54       SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

too  much,,  a  mistake  too  often  made  by  cheese- 
makers.  Milk  which  is  overripe,  whether  at  the 
time  of  delivery  or  as  the  result  of  ripening  after 
delivery,  is  difficult  to  handle  (p.  122).  In  the 
methods  often  employed,  much  loss  of  fat  is  often 
experienced  in  order  not  to  sacrifice  quality  in  cheese. 
The  use  of  commercial  starters  (p.  19)  gives  the  most 
reliable  results  in  ripening  milk. 

(3)  Control  of  whey. — The  degree  of  acidity  in 
curd    and   cheese    is    primarily    dependent    upon    the 
amount  of  whey  retained,  and  control  of  the  amount 
of  whey  really  means  control  of  acidity.     The  methods 
for  this  have  been  given   (p.  48). 

(4)  Amount   of   acid   at   different  stages. — The 
degree  of  acidity  should  be  kept  under  careful  con- 
trol   at    each    stage    of    the    operations    of    cheese- 
making,    which    is    done    by    careful    regulation    of 
temperature    and     the     different     prescribed     manip- 
ulations of  the  curd.     There  must  be  a  careful  ad- 
justment    of     conditions     in     respect    to     (i)     the 
rapidity    of    formation    and    thickening    of    the    film 
around   the   pieces   of   curd,    (2)    the   contraction    of 
the    curd,    (3)    the  expulsion  of  whey,  and   (4)   the 
degree  of  acidity. 


CHAPTER  VI 

Modifications  of  Cheddar  Process  and 
Miscellaneous  Subjects 

In  describing  and  discussing  in  detail  the  various 
operations  involved  in  making  American  cheddar 
cheese,  it  has  seemed  best  to  reserve  for  a  special 
chapter  several  subjects  which  are  more  or  less 
closely  related  to  this  method  of  cheese-making, 
but  which  do  not  form  an  essential  part  of  it.  Of 
the  many  topics  which  might  come  in  this  chapter, 
the  following  have  been  selected  for  consideration: 
(i)  "Stirred-curd"  method;  (2)  "soaked-curd" 
method;  (3)  pasteurized  milk  in  cheese-making; 
(4)  slow-ripening  and  quick-ripening  cheese;  (5) 
home-trade  cheese;  (6)  use  of  artificial  acids  in 
cheddar  cheese-making;  (7)  the  use  of  pepsin  in 
cheddar  cheese-making;  (8)  whey  butter;  (9)  dis- 
tribution and  value  of  whey;  (10)  cheese  poison; 
(u)  starters  in  relation  to  yield  of  cheese;  (12) 
making  butter  and  cheese. 

THE    "STIRRED-CURD"    OR    "GRANULAR" 
PROCESS   OF  CHEESE-MAKING 

This  process  was  exclusively  used  in  America 
for  many  years  and  is  still  in  operation  in  some 
cheese-factories.  While  it  is  not  our  purpose  to 
present  a  detailed  description  of  this  method,  it  is 
desirable,  as  a  matter  of  information,  to  state  its 

66 


56        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


most  essential  points,  especially  those  in  which  it 
differs  from  the  cheddar  method.  The  cheddar  and 
stirred-curd  methods  are  identical  until  the  time 
comes  for  the  removal  of  the  whey  from  the  curd, 
when  they  differ  in  the  following  respects :  ( i )  In 
the  cheddar  process  the  whey  is  removed  from  the 
curd  when  the  hot-iron  test  shows  strings  }fa  to  J4 
inch  long;  in  the  stirred-curd  process,  the  curd  re- 
mains longer  in  the  whey,  until  the  hot-iron  test 
shows  strings  y2  to  i  inch  long.  (2)  After  the  re- 
moval of  whey,  the  curd,  in  the  cheddar  process,  is 
packed  and  then  cheddared ;  while,  in  the  stirred- 
curd  process,  the  curd  is  transferred  to  a  curd-sink 
and  is  more  or  less  frequently  stirred,  so  that  the 
small  pieces  are  kept  separate;  and  at  no  time  is 
the  curd  permitted  to  pack  in  a  solid  mass.  The 
main  object  of  keeping  the  curd  longer  in  the  whey 
is  to  firm  the  curd  to  such  an  extent  that  it  can  be 
kept  in  the  "granular"  form  more  easily.  (3)  In  the 
cheddar  process,  the  time  between  the  removal  of 
whey  and  salting  is  much  longer  than  in  the  stirred- 
curd  method;  while  (4)  the  time  between  salting 
and  pressing  curd  is  much  longer  in  the  stirred- 
curd  process.  These  general  differences  are  well 


Method  used 

Time  from  reach- 
ing 98°  F.  to  re- 
moving whey 
from  curd 

Time  from  remov- 
ing whey  to  salt- 
ing curd 

Time  from  salting 
to  pressing 
curd 

Cheddar  
Stirred-curd  
Cheddar  
Stirred-curd  .... 
Cheddar  

Minutes 
90 
175 
62 
100 
90 

Minutes 
200 
25 
133 
15 
230 

Minutes 
30 
95 
10 
100 
30 

Stirred-curd  .... 

164 

25 

140 

MISCELLANEOUS    SUBJECTS  57 

illustrated  by  the  foregoing  dataj  which  were  ob- 
tained at  the  New  York  experiment  station  in  mak- 
ing different  portions  of  the  same  milk  into  cheese 
by  these  two  methods. 

It  will  be  noticed  that,  in  general,  the  total  amount 
of  time  consumed  is  about  the  same  by  either 
method.  The  time  is  simply  distributed  differently 
at  certain  stages  of  the  work. 

It  is  much  more  difficult  with  this  method  to 
make  cheese  of  perfect  texture,  at  least  considered 
from  the  standpoint  of  the  type  of  cheese  intended 
for  export.  It  was  the  influence  of  the  demands 
of  the  English  market  which  caused  American 
cheese-makers  to  change  from  the  stirred-curd  to 
the  cheddar  method.  The  cheddar  process  has  the 
marked  advantage  of  enabling  the  cheese-maker 
to  control  his  operations  more  completely  and  pro- 
duce cheese  of  close  texture.  Greater  skill  is  re- 
quired to  produce  results  by  the  stirred-curd  method 
equal  to  those  obtained  with  the  cheddar  method. 
Under  ordinary  conditions,  the  stirred-curd  method 
produces  cheese  with  a  little  higher  content  of  mois- 
ture, but  not  necessarily  so.  The  loss  of  fat  is  the 
same  by  either  method. 

THE     "SOAKED-CURD"     METHOD 

This  is  a  modification  of  the  cheddar  method, 
which  has  for  its  object  an  increase  of  water  other 
than  that  derived  from  the  whey.  It  is  to  be  dis- 
tinguished from  the  advantageous  practice  of  wash- 
ing curd  in  the  case  of  abnormal  flavor,  excessive 
acidity,  etc.  It  is  applied  to  both  skim-milk  and 


58       SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


normal-milk  cheese.  The  process  is  simply  this: 
When  the  curd  has  matured  ready  for  salting,  it  is 
covered  with  cold  water  and  allowed  to  soak  10  to 
15  minutes.  In  this  way  the  amount  of  water  in 
100  pounds  of  cheese  can  be  increased  ordinarily 
4  or  5  pounds,  producing  a  cheese  with  41  to  44 
per  cent  of  water.  The  soaking  of  curd  by  this 


FIG.  9 

Showing  the  effect  of  excessive  moisture  in  a  soaked-curd  cheese  upon  the 
body.  The  cheese  with  normal  moisture  keeps  its  shape  perfectly.  The  soaked- 
curd  cheese  bulges  at  the  sides  and  flattens  down  if  kept  at  temperatures  65  or  70 
degrees  F. 

process  not  only  increases  the  yield  of  cheese  by 
the  incorporation  of  water  other  than  what  was  a 
part  of  the  original  milk  from  which  the  cheese  was 
made,  but  it  also  dissolves  from  the  curd  (i)  milk- 
sugar;  and  (2)  the  soluble  calcium  salts,  especially 
acid  calcium  phosphate.  These  normal  cheese  con- 
stituents, which  are  thus  removed  from  the  curd, 
are  essential  to  the  normal  ripening  process  of  the 


MISCELLANEOUS   SUBJECTS  59 

cheese  and,  in  their  absence,  cheese  undergoes  ab- 
normal fermentations  as  the  result  of  the  action  of 
putrefactive  bacteria.  These  facts  have  been  es- 
tablished by  work  done  at  the  Cornell  University 
experiment  station.  This  practice  has  been  de- 
fended on  the  ground  of  removing  undesirable  "im- 
purities" carried  into  the  cheese  by  the  whey.  This 
is  a  pure  assumption  which  has  no  foundation  in 


FIG.    10 

Showing  the  difference  between  the  close  textiire  of  normal  cheese  and  the 
loose,  spongy  texture  of  a  soaked-curd  cheese. 

fact.  The  whey-solids,  thus  miscalled  "impurities," 
are  normal  constituents  of  cheese  and  are  necessary 
to  the  completion  of  the  ripening  process  when 
present  in  normal  amount.  Cheese  made  by  the 
soaked-curd  process  is  very  properly  not  permitted 
the  use  of  the  brand  designed  for  whole-milk  cheese 
in  New  York  state,  on  the  following  grounds:  (i) 
Water  other  than  that  present  in  the  original  milk 
from  which  the  cheese  was  made  .is  incorporated 
with  the  cheese  for  the  purpose  of  increasing  its 


6o        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

weight  without  improving  its  quality;  and  (2)  the 
soaking  process  removes  normal  constituents  that  are 
essential  to  the  ripening  of  the  cheese.  These  grounds 
are  based  upon  established  facts. 

Cheese  produced  by  the  soaked-curd  process 
usually  exhibits  the  defects  characteristic  of  cheese 
containing  an  excessive  amount  of  moisture;  these 
are  weak  body  and  loose  texture  (pp.  86-87).  When 
kept  at  temperatures  above  65°  or  70°  F.,  such 
cheese  fails  to  stand  up  like  normal  cheese  and  it 
also  suffers  in  texture  from  the  effects  of  gassy  fer- 
mentations. Figs.  9  and  10  well  illustrate  the  truth 
of  these  statements.  They  represent  work  done  at 
the  Cornell  University  experiment  station  with 
cheese  made  according  to  the  soaked-curd  method. 

CHEDDAR    CHEESE    FROM    PASTEURIZED 
MILK 

Many  attempts  have  been  made  to  manufacture 
cheddar  cheese  from  pasteurized  milk.  The  results 
in  America  have  not  been  wholly  encouraging  up  to 
the  present  time.  The  cheese  is  generally  imperfect 
in  body,  lacking  in  flavor  and  slow  in  ripening.  We 
do  not,  therefore,  think  it  desirable  to  devote  'fur- 
ther attention  to  the  various  modifications  of  details 
required  in  its  manufacture.  It  is  said  that  much 
skim-milk  cheese  is  successfully  made  in  Denmark 
from  pasteurized  milk. 

CONDITIONS        OF       CHEESE-MAKING 

PROCESS     FOR     QUICK-RIPENING 

AND    SLOW-RIPENING    CHEESE 

Certain  conditions  of  the  cheese-making  process 
promote,  while  others  retard,  the  rapidity  of  ripen- 


MISCELLANEOUS    SUBJECTS  6l 

ing.  The  general  relation  of  different  conditions  to 
the  rapid  or  slow  rate  of  cheese-ripening  may  be 
shown  by  the  following  form  of  statement: 

Conditions  that  may  Conditions  that  may 
promote  ripening:  retard  ripening: 

(1)  Increase  of  ripening     (i)   Decrease    of    ripen- 

temperature.  ing  temperature. 

(2)  Larger    amount    of     (2)  Smaller    amount    of 

rennet.  rennet. 

(3)  More     moisture     in     (3)   Less     moisture     in 

cheese.  cheese. 

(4)  Less  salt.  (4)  More  salt. 

(5)  Large        «ize        of     (5)  Small  size  of  cheese. 

cheese. 

(6)  Moderate  amount  of     (6)  Deficient  acidity  or 

acid.  excess  of  acidity. 

If  a  cheese  is  desired  that  ripens  quickly,  it 
should  contain  more  than  the  usual  amount  of  ren- 
net, a  moisture  content  of  about  40  per  cent  or 
more,  and  about  i  to  iy2  pounds  of  salt  for  1,000 
pounds  of  milk.  Then  it  should  be  kept  at  a  tem- 
perature between  60°  F.  and  70°  F.,  if  it  is  to  be 
placed  in  the  hands  of  consumers  in  one  month  or 
six  weeks,  and  the  atmosphere  of  the  curing-room 
should  have  a  humidity  of  75  to  85  per  cent  of 
saturation.  However,  it  should  be  stated  that 
cheese  made  to  ripen  quickly  gives  better  results 
in  commercial  quality  when  ripened  at  a  lower 
temperature  than  60°  F.  and  held  a  longer 
time. 

For  a  slow-ripening  cheese,  not  more  than  2l/2 
ounces  of  rennet-extract,  such  as  Hansen's,  should 


62        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

be  used  for  1,000  pounds  of  milk,  and  about  2  to  2^2 
pounds  of  salt.  The  other  conditions  that  influence 
the  moisture  content  of  cheese,  such  as  the  tem- 
perature of  heating  the  curd,  the  fineness  of  cutting 
curd,  the  amount  of  acid  developed  in  the  curd, 
cheddaring,  etc.  (p.  45),  should  be  well  under 
control,  so  as  to  produce  a  cheese  containing,  when 
fresh  from  the  press,  about  37  per  cent  of  water.  For 
ripening,  it  should  be  kept  at  a  temperature  below  50° 
F.  in  a  fairly  moist  atmosphere  for  a  period  of  3  to  6 
months  or  more. 

HOME-TRADE  CHEESE 

The  majority  of  cheese  consumers  desire  a  cheese 
soft  in  body  and  with  a  mild,  clean  flavor.  Soft- 
ness is  synonymous  with  richness  in  cheese  to 
most  people.  While  it  is  true  that  cheese  rich  in 
fat  possesses  a  characteristic  softness,  it  is  not  true 
that  all  soft  cheese  is  rich  in  fat.  The  desire  for  a 
mild-flavored  cheese  is  a  reaction  from  the  taste 
for  a  cheese  of  strong,  pungent  flavor.  To  meet  in 
the  easiest  way  the  demand  for  soft-bodied,  mild- 
flavored  cheese,  there  has  arisen  quite  an  extensive 
manufacture  of  what  is  known  as  "home-trade" 
cheese.  The  method  of  making  this  kind  of  cheese 
varies  in  its  details  in  different  localities,  but  the 
general  object  is  the  production  of  a  quick-curing 
cheese  which  will  be  ready  for  consumption  in  four 
to  six  weeks.  The  distinctive  characteristics  of 
such  cheese  are  its  high  water  content,  a  conse- 
quent softness  of  body  and  open  texture,  a  mild 
flavor  when  a  few  weeks  old,  and  a  poor-keeping 
quality.  These  results  are  attained,  in  general,  by 


MISCELLANEOUS    SUBJECTS  -63 

using  large  amounts  of  rennet-extract,  developing 
less  acidity,  heating  the  curd  in  the  whey  to  103° 
to  110°  F.  and  ripening  at  60°  to  70°  F.  In  many 
cases,  where  the  conditions  of  ripening  are  not  un- 
der confrol,  home-trade  cheese  is  made  only  in  the 
fall,  since  there  is  less  risk  in  handling  the  ripening 
process  at  a  time  when  the  temperature  is  not  high. 
Home-trade  cheese,  when  green,  usually  contains 
38  to  40  per  cent  of  water,  but  the  percentage  may 
run  up  to  43  or  even  45.  The  fact  that  this  soft 
cheese  is  more  extensively  made  in  the  fall  has  led 
cheese-makers  to  believe  that,  "milk  very  rich  in  fat, 
such  as  strippers'  milk,  is  liable  to  cause  a  pasty 
cheese."  Such  a  belief  could  hardly  be  further  from 
the  truth,  as  shown  by  the  facts  given  in  Chapter 
XV,  pp.  164-167,  where  the  influence  of  advancing 
lactation  on  the  composition  of  milk  is  discussed. 

It  should  be  stated  in  this  connection  that,  in  New 
York  state,  a  large  proportion  of  the  cheese  made 
under  the  name  of  home-trade  is  of  a  type  quite  dif- 
ferent from  that  described  above.  In  the  process 
of  making,  the  temperature  is  not  allowed  to  go  above 
98°  F.  and  the  percentage  of  moisture  is  kept  at  38 
to  40.  The  resulting  cheese  is  firm-bodied,  close-tex- 
tured and  of  good-keeping  quality.  It  is  the  best 
type  of  home-trade  cheese  and  is  in  large  demand. 

USE  OF  ARTIFICIAL  ACIDS  IN   CHEDDAR 
CHEESE-MAKING 

Attempts  have  been  made  to  use  artificial  lactic 
and  other  acids  in  making  cheddar  cheese,  in  order 
to  hasten  the  cheese-making  operations.  Theoreti- 
cally, the  addition  of  small  amounts  of  dilute  acid 


64        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

can  take  the  place  of  starters  in  hastening  the  ac- 
tion of  rennet,  and,  to  some  extent,  in  the  subse- 
quent stages.  While  it  is  possible  to  assist  the  lactic 
acid  bacteria  in  this  way,  great  caution  is  required. 
The  addition  of  too  much  acid  results  in  the  produc- 
tion of  cheese  that  does  not  ripen.  So  far  as  we 
know,  the  application  of  artificial  acids  in  cheddar 
cheese-making  has  never  been  worked  out  to  such 
an  extent  that  all  details  are  under  control.  While 
cheese  of  good  quality  can  be  made  in  this  way,  there 
is  probably  no  advantage,  even  when  the  process  is 
under  absolute  control;  and,  in  the  absence  of  such 
control,  no  one  should  ever  attempt  to  employ  such  a 
method  in  practical  work. 

USE    OF    PEPSIN    IN    CHEDDAR    CHEESE- 
MAKING 

Commercial  pepsin  prepared  from  the  stomachs 
of  sheep  has  been  successfully  used  in  place  of  ren- 
net-extract in  making  cheddar  cheese.  The  special 
pepsin  most  used  in  this  way  is  a  scale-pepsin 
known  as  1-3000  strength.  Five  grams  of  this  pep- 
sin equal  the  coagulating  power  of  3  ounces  of 
Hansen's  rennet-extract.  The  pepsin  is  dissolved 
in  cold  water  for  use.  In  using  pepsin,  one  should 
make  a  solution  and  test  it  in  comparison  with  ren- 
net-extract on  the  same  milk.  (Modern  Methods 
of  Testing  Milk,  etc.,  pp.  125-126.)  Pepsin  has  the 
following  advantages  over  rennet-extract:  (i)  It 
is  more  concentrated  and,  therefore,  more  conven- 
ient and  less  expensive  to  ship.  (2)  If  kept  dry, 
pepsin  retains  its  strength  indefinitely,  while  ren- 
net-extract does  not.  These  advantages  of  pepsin 


MISCELLANEOUS    SUBJECTS  65 

over  rennet-extract  do  not,  of  course,  apply  to  ren- 
net powders.  The  quality  of  cheese  made  by  use  of 
pepsin  does  not  appear  to  be  inferior  to  that  made 
by  the  use  of  rennet.  Commercial  pepsin  is  probably 
more  expensive  to  use  than  rennet-extract  and  is  not 
uniform  in  strength. 

MANUFACTURE  OF  WHEY-BUTTER 

The  fat  in  whey  can  be  readily  removed,  in  large 
part,  by  means  of  a  centrifugal  separator,  and  the 
resulting  cream  can  be  made  into  butter  in  much 
the  same  manner  as  cream  separated  directly  from 
milk.  The  butter  thus  made  is  apt  to  be  somewhat 
softer  than  in  case  of  normal  butter ;  the  flavor  is 
fair  to  good.  From  the  whey  produced  in  making 
10,000  pounds  of  milk  into  cheese  under  normal  con- 
ditions, about  25  to  30  pounds  of  whey-butter  can 
be  made  under  favorable  conditions.  This  yield  is 
based  upon  an  average  loss  of  0.3  pound  of  fat  in 
whey  for  100  pounds  of  milk  (p.  189).  The  removal 
of  milk-fat  from  whey  does  not  greatly  reduce  its 
feeding  value. 

The  question  of  making  whey-butter  is  largely  a 
matter  of  cost  of  production.  In  the  case  of  small 
cheese-factories,  the  yield  of  butter  would  not 
repay  the  labor.  In  larger  factories,  it  would  be- 
come, to  some  extent,  a  question  of  the  amount 
of  fat  in  the  whey.  In  general,  it  may  be  said 
that  the  manufacture  of  whey-butter  will  be 
usually  found  profitable  under  the  following  con- 
ditions : 

(i)  When  the  daily  average  milk  supply  is  not 
less  than  10,000  pounds  and  the  amount  of  fat  in 


66       SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

whey  averages  0.25  pound  or  more  for  100  pounds  .of 
milk. 

(2)  When    the    average    cost    of    making    whey- 
butter  can  be  kept  sufficiently  low.     The  usual  cost 
is  5  to  8  cents  a  pound,  including  cost  of  fuel,  labor, 
coloring-matter,  salt,  etc.     Among  the  conditions  that 
favor  economy  of  production  are  the  following:     (a) 
A  building  so   located   and   constructed   that   gravity 
can  be  used  to  carry  whey  to  and  from  the  separator 
at  minimum  cost;     (b)    a  cheap  supply  of  pure   ice 
and  cold  water;    (c)   the  possession  of  a  centrifugal 
separator  and   a  butter-making  equipment  as  a  part 
of  the  factory  plant;    (d)  reasonable  cost  of  fuel  and 
labor. 

(3)  When    a   gooo    quality    of    butter    is    made. 
This,  of  course,  requires   pasteurization  of  cream,  the 
use  of  a  good  commercial  starter,  extreme  cleanliness 
at  every  stage  of  the  butter-making  process  and  proper 
sanitary  surroundings. 

In  St.  Lawrence  County,  New  York,  several  fac- 
tories have  formed  a  combination  for  the  successful 
manufacture  of  whey-butter.  The  separated  cream  is 
sent  by  each  to  a  central  butter-making  station.  When 
all  conditions  are  favorable,  a  cheese-factory  receiving 
10,000  pounds  of  milk  a  day  on  the  average,  could 
with  profit  install  the  equipment  necessary  for  making 
whey-butter. 

DISTRIBUTION  AND   VALUE  OF  WHEY 

The  theoretical  yield  of  whey  for  100  pounds  of 
milk  averages  about  90  pounds,  with  a  variation 
between  87  and  91.5  pounds,  according  to  the  yield 


MISCELLANEOUS    SUBJECTS  67 

of  cheese  for  100  pounds  of  milk.  The  theoretical 
yield  is  reduced  by  the  losses  in  the  cheese-making 
operations,  due  (i)  to  evaporation  of  water  and 
(2)  to  mechanical  losses.  The  yield  of  whey  varies 
with  the  composition  of  the  milk  and,  therefore, 
with  the  time  of  season  and  other  conditions  that 
affect  the  composition  of  milk  (p.  204).  In  gen- 
eral, it  is  safe  to  say  that  the  yield  of  whey  is  about 
88  pounds  for  100  pounds  of  milk,  taking  the  sea- 
son as  a  whole;  but  this  yield  is  considerably 
reduced  by  losses  in  handling.  In  allowing  each 
patron  to  take  the  portion  of  whey  coming  to  him, 
the  usual  amount  is  80  to  85  pounds  for  100  pounds 
of  milk  delivered.  Where  the  whey  is  valued  by 
every  patron,  it  is  essential  that  each  one  be  as- 
signed his  just  portion  ;  otherwise  some  will  always 
take  more  than  belongs  to  them.  There  are  various 
satisfactory  devices  for  controlling  the  amount  of 
whey  each  patron  can  take. 

The  chief  value  of  whey  to  patrons  is  as  material 
for  feeding  pigs  and  calves  in  connection  with 
other  foods.  The  feeding  value  of  sweet  whey 
may  be  conservatively  placed  at  8  to  10  cents  for 
100  pounds.  For  the  composition  of  whey,  see 
p.  197.  Whey  sours  rapidly  and  loses  a  consider- 
able amount  of  its  milk-sugar  under  ordinary  con- 
ditions. In  order  that  its  highest  food  value  >may 
be  realized,  it  is  essential  that  it  should  be  pasteur- 
ized promptly  at  155°  to  158°  F.  and  the  whey- vat 
always  kept  in  clean  condition  (p.  127).  It  is  not  prac- 
ticable to  sterilize  whey,  because  the  heat  needed  for 
sterilization  coagulates  the  albumin.  Whey  that  is  de- 
cidedly sour  often  has  an  injurious  effect  on  the  animals 


68        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

to  which  it  is  fed,  especially  when  fed  alone  and 
in  excess,  -There  is  another  even  more  important 
reason  why  whey  should  be  pasteurized.  The 
whey-vat  has  been  known  to  become  a  distributing 
source  of  disease  among"  calves  and  pigs  and  of  ab- 
normal fermentations  that  injure  the  quality  of  cheese. 
Sweet  whey  has  a  value  of  6  or  7  cents  per  100  pounds 
when  sold  for  the  manufacture  of  milk-sugar,  but  com- 
paratively little  whey  can  be  actually  disposed  of  in 
this  way. 

CHEESE  POISON 

For  a  long  time  it  was  known  that  cheese  some- 
times acts  as  a  violent  poison,  but  it  was  not  until 
about  25  years  ago  that  a  specific  poisonous  com- 
pound was  isolated  from  cheese.  Many  cases  of 
cheese  poisoning  had  occurred  in  Michigan  at  the 
time  and  the  matter  was  investigated  by  Dr.  V.  C. 
Vaughan,  professor  of  physiological  chemistry  at 
the  University  of  Michigan,  who  succeeded  in  sepa- 
rating from  some  of  the  poisonous  cheese  an  in- 
tensely poisonous  compound,  which  he  called  tyro- 
toxicon  (cheese  poison).  The  poison  is  present  in 
cheese  in  only  very  minute  amounts,  but  is  intensely 
powerful.  A  drop  of  a  highly  dilute  solution  of  this 
poison  placed  on  the  tongue  produces  a  characteristic 
benumbing  sensation.  This  poison  is  the  result  of 
bacterial  action  and  is  produced  only  by  those  bacteria 
,which  are  associated  with  conditions  of  filth.  There 
are  sometimes  also  other  poisons  in  cheese,  less  well 
known. 


MISCELLANEOUS    SUBJECTS  69 

STARTERS    IN    RELATION    TO    YIELD    OF 
CHEESE 

When  a  cheese-maker  uses  comparatively  large 
amounts  of  starter,  as  5  pounds  for  100  pounds  of 
milk,  the  question  arises  as  to  whether  this  does 
not  increase  the  yield  of  cheese  and  is  not  practi- 
cally equivalent  to  adding"  the  same  amount  of 
skim-milk.  The  amount  of  added  casein  thus  intro- 
duced is  about  2  ounces  and  is  equivalent  to.  an 
increased  yield  of  cheese  amounting1  to  about  5 
ounces  for  100  pounds  of  milk.  Theoretically,  the 
practice  of  adding  large  amounts  of  starter  might 
lead  to  abuse ;  but  rennet-extract  does  not  act  upon 
the  coagulated  casein  of  sour  milk  or  of  buttermilk. 
The  casein  contained  in  the  starter,  although  held 
fast  in  the  coagulum  at  first,  separates  to  a  large 
extent  during  the  cheese-making  in  the  form  of 
fine  particles.  When  a  large  amount  of  starter  is 
used,  these  small  particles  are  very  noticeable  in 
the  whey.  The  fact  that  the  addition  of  a  starter 
to  milk  does  not  increase  the  yield  of  cheese  has 
been  brought  out  by  work  done  in  the  dairy  de- 
partment at  the  Cornell  University  experiment 
station. 

MAKING  BUTTER  AND  CHEESE 

The  question  is  often  raised  as  to  whether  or  not 
it  pays  to  remove  a  part  of  the  fat  from  milk  and 
make  butter  and  part-skim  cheese.  As  a  rule,  it 
does  not  pay,  unless  one  sells  the  part-skim  cheese 
for  whole-milk  cheese,  and  this  is  very  difficult  to 
do  now  under  our  pure-food  laws.  The  best  advice 


70        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

that  can  be  given  is  to  make  either  butter  or  cheese, 
but  not  to  mix  the  manufacture  of  the  two  products. 
Some  cheese-factories  drop  cheese-making  in  the 
fall  and  make  butter  during  the  winter.  The  rela- 
tive price  of  cheese  and  butter  will  determine  which 
pays  better.  In  general,  it  can  be  said  that  butter- 
making  pays  better  than  cheese-making  whenever  the 
price  of  butter  is  greater  than  two  and  one-third 
times  the  price  of  cheese  per  pound.  For  example, 
when  cheese  sells  at  10  cents  a  pound,  butter-making 
will  pay  better/ if  the  price  of  butter  is  above  23  1-3 
cents  a  pound. 


CHAPTER  VII 

Care,  Shipment  and  Sale  of  Cheese 

It  has  been  said  that  a  cheese  is  really  only  half 
made  when  it  is  taken  from  the  press.  This  is,  in  a 
great  measure,  true,  because  the  conditions  of  tem- 
perature and  humidity  to  which  a  cheese  is  sub- 
jected during  the  process  of  ripening  or  curing 
largely  determine  its  quality.  An  excellent  cheese 
may  be  absolutely  spoiled  by  unfavorable  ripening 
conditions,  while  a  cheese  of  inferior  quality  may 
be  much  improved  by  being  kept  under  favorable 
conditions.  The  subject  of  cheese-ripening  in  its 
practical  relations  is  discussed  in  Chapter  XXVI, 
PP-  379-394- 

CLEANING  THE  SURFACE 

When  each  cheese  is  taken  from  the  press,  it  should 
be  wiped  off  with  a  dry  cloth,  and  any  rust-spots  or 
finger-marks  removed.  Deep-seated  spots  of  dirt  can 
be  more  easily  removed  by  the  use  of  a  brush  and  hot 
water. 

PLACING    CHEESE    IN    CURING-ROOM 

No  cheese  should  be  placed  in  the  curing-room 
until  it  is  clean  and  well  finished.  A  badly  finished 
or  dirty  cheese  never  attracts  a  cteese  buyer,  in- 
spector or  consumer.  Imperfections  in  quality  are 

71 


72        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

often  overlooked  if  the  finish  and  general  appearance 
are  good. 

When  cheese  is  placed  in  the  curing-room,  it 
should  be  arranged  in  a  neat  manner  upon  clean 
shelves  or  tables.  Too  many  cheese-makers  allow 
the  cheese-shelves  to  become  moldy  and  dirty ;  con- 
sequently, when  a  clean  cheese  is  placed  on  them  the 
end  surfaces  soon  become  stained  and  dirty.  The 
shelves  should  be  thoroughly  cleaned  after  each  ship- 
ment of  cheese  leaves  the  factory. 

TURNING     CHEESE     DURING     RIPENING 
PROCESS 

Each  cheese  should  be  turned  on  the  shelf  every 
morning  until  ready  for  shipment.  At  the  time  of 
turning,  if  an  excess  of  moisture  or  any  mold  is 
present,  it  should  be  wiped  off  with  a  dry  cloth,  or 
with  a  damp  one  wrung  out  of  a  10  per  cent  solution 
of  formaldehyd. 

MARKING  DATE  OF  MANUFACTURE 

When  cheese  is  placed  in  the  curing-room,  the 
date  of  its  manufacture  should  be  stamped  on  each, 
so  as  to  correspond  with  the  number  of  the  manufac- 
turing record  of  the  same  date  and  thus  avoid  errors 
in  shipment. 

USE  OF  CHEESE  BRANDS 

Many  states  have  statutes  providing  for  the 
branding  of  cheese.  The  brand  usually  indicates 
whether  the  ch*eese  has  been  made  from  whole 


CARE,    SHIPMENT    AND    SALE    OF    CHEESE  73 

milk  or  skimmed  milk.  Brass  stencils  for  this  pur- 
pose are  usually  sent  to  factories  by  the  state  de- 
partments of  agriculture,  which  keep  a  record  of 
the  number  of  each  factory,  and  this  particular 
number  appears  as  part  of  the  brand.  This  is  to 
protect  the  manufacturers  of  whole-milk  cheese 
from  dishonest  competition  with  those  who  remove 
part  or  all  of  the  fat  from  the  milk  before  making 
it  into  cheese.  In  Canada  many  factories  stamp 
the  name  of  the  factory  on  the  cheese.  In  many 
instances,  this  is  a  good  plan,  if  the  quality  of  the 
cheese  is  good,  but  disastrous  if  the  cheese  is  defec- 
tive in  quality. 

WHEN  CHEESE  SHOULD  BE  SHIPPED 

The  age  at  which  cheese  should  be  shipped  from 
the  factory  depends  on  several  conditions.  If  the 
curing-room  is  one  in  which  the  temperature  and 
humidity  cannot  be  controlled  at  all,  the  cheese 
should  be  shipped  within  a  few  days  to  some  place 
where  it  can  be  kept  under  proper  conditions.  In 
some  places,  central  cold  storages  are  located 
where  cheese,  either  before  or  after  selling,  is  sent 
to  ripen.  If  the  temperature  in  the  cheese-factory 
can  be  controlled,  the  cheese  should  not  be  shipped 
so  soon.  Cheese  10  days  old  is  young  enough,  and, 
if  for  export,  two  weeks  will  be  much  better.  An 
export  cheese  is  not  very  palatable  in  less  than  one 
month.  A  home-trade  cheese  containing  a  high 
percentage  of  moisture  may  be  ready  at  an  earlier 
date  (p.  62) 

During  the  past  few  years,  complaints,  in  increas- 
ing number,  have  been  made  by  foreign  cheese 


74          SCIENCE   AND   PRACTICE    OF    CHEESE-MAKING 

merchants,  who  say  that  cheese  is  shipped  to  them 
before  it  is  old  enough.  The  Canadian  govern- 
ment has  lately  been  making  vigorous  efforts  to 
overcome  this  practice,  which  has  become  too  com- 
mon. The  important  point  to  be  kept  in  mind  is 
that  the  cheese  should  be  in  an  edible  condition  when 
it  reaches  the  consumer. 


FIG.    11 — DAIRY  STUDENTS  WEIGHING,  PARAFFINING  AND  BOXING 
CHEESE 

COVERING    CHEESE   WITH    PARAFFIN 

Loss  of  moisture  in  cheese  can  be  largely  pre- 
vented by  coating  the  cheese  with  a  thin  layer  of 
paraffin,  and  this  can  be  done  without  injuring  the 
quality.  The  higher  the  temperature,  the  greater 
is  the  prevention  of  loss.  Another  distinct  advantage 


in  using  paraffin  is  that  it  prevents  cheese  becom- 
ing moldy.  The  cheese  is  allowed  to  dry  well  on 
the  surface  and  is  then  dipped  for  8  to  15  seconds, 
according  to  the  size  and  temperature  of  the 
cheese,  in  melted  paraffin  at  a  temperature  of  at 


TQ 


FIG.  12 — APPARATUS  FOR  PARAFFINING  CHEESE 

least  220°  F.  Care  must  be  taken  to  keep  the  par- 
affin from  acquiring  a  disagreeable  odor  as  a  result 
of  overheating.  Cheese  should  be  dry  enough  in 
three  to  seven  days  to  be  ready  for  paraffining,  but 
the  time  will  depend,  of  course,  on  the  amount  of 
moisture  in  the  cheese  and  in  the  curing-room.  The 
application  of  paraffin  at  a  high  temperature  gives 
a  thin  coating  that  adheres  tenaciously  and  de- 
-stroys  mold  formation.  If  the  temperature  is  too 


76        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

low,  the  coating  will  be  too  thick  and  will  crack  or 
break  away  from  the  cheese  more  easily.  About 
5  or  6  ounces  of  paraffin  will  cover  an  8o-pound 
cheese,  and  the  cost  is  about  2.y2  to  3  cents.  Most 
retail  merchants  are  now  in  favor  of  having"  cheese 
coated  with  paraffin ;  but  in  England  many  of  the 
large  exporters  are  not  in  sympathy  with  the  idea, 
although  the  number  of  the  latter  is  gradually  de- 
creasing. If  cheese  is  exposed  to  high  tempera- 
tures after  the  paraffin  is  applied,  its  beneficial  effect 
will  be  lost.  For  this  reason,  the  average  factory 
cannot  paraffin  cheese,  and  it  is  usually  done  at 
central  cold-storage  places,  to  which  the  cheese  is 
shipped. 

WEIGHING  CHEESE  FOR  SHIPMENT 

Before  cheese  is  shipped,  each  one  should  be 
carefully  weighed  and  the  weights  copied  in  dupli- 
cate.. Special  cheese-shipping  books  are  available 
for  this  purpose.  One  copy  is  forwarded  to  the 
purchaser  of  the  cheese  and  the  other  is  kept  at 
the  cheese-factory.  In  most  states,  the  cheese  is  sold 
according  to  the  exact  weight  of  each,  "balanced 
beam."  In  Canada  the  factorymen  are  forced  to 
allow  the  buyers  "up-beam,"  plus  *4  pound.  This 
means  that,  for  every  cheese  sold,  the  factoryman 
gives  away  at  least  *4  pound.  In  many  cases  it  is 
more,  because  it  is  difficult  for  the  cheese-maker  to 
have  the  cheese  always  weigh  so  near  the  pound  mark. 
Unfortunately,  this  has  become  an  almost  uncriticised 
practice  and  it  is  hoped  that  cheese-makers  in 
Canada  will  soon  awaken  to  a  better  method  of  selling 
cheese. 


CARE/    SHIPMENT    AND     SALE     OF     CHEESE  77 

BOXING    CHEESE    FOR    SHIPMENT 

After  cheese  is  weighed,  each  is  placed  in  a  box 
for  shipment.  A  thin  scale-board  should  be  placed 
between  the  cheese  and  each  end  of  the  box  to 
prevent  the  cheese  sticking  to  the  box.  The  box 
should  fit  the  cheese  closely  and  should  be  strong 
enough  to  stand  shipment  without  breaking.  If 
the  box  is  too  high,  it  should  be  pared  down  with 
a  draw-knife.  The  lid  of  the  box  should  just  press 
lightly  on  the  top  of  the  cheese.  Some  shipping 
companies  demand  that  the  lids  be  securely  fastened 
on  every  box.  If  the  lids  fit  snugly,  they  will 
not  come  off  easily  in  handling;  but  if  nails  are 
used,  they  should  not  be  so  long  as  to  penetrate  the 
cheese. 

STENCILING  THE  BOXES 

The  weight  of  the  cheese  should  be  neatly 
stenciled  on  the  side  of  the  box  in  large  figures 
and,  if  the  cheese  is  for  export,  the  name  of  the 
factory  should  also  be  stenciled  on  the  side.  It  is 
bad  practice  to  mark  the  weights  with  a  lead 
pencil.  Such  marks  do  not  look  well  and  are  often 
very  indistinct,  since  all  cheese-makers  cannot 
make  neat,  plain  figures.  A  rubber  stamp  is,  per- 
haps, the  quickest  and  neatest  way.  If  a  brass 
stencil  is  used,  a  mixture  of  coal-oil  and  lamp- 
black makes  a  very  suitable  blacking.  Shoe-black- 
ing should  not  be  used,  because  it  easily  becomes 
smeared  and  then  makes  the  package  appear  un- 
tidy. 


78         SCIENCE   AND   PRACTICE   OF    CHEESE-MAKING 


DRAWING   CHEESE   TO    SHIPPING   POINT 

Most  cheese-factories  are  located  in  country 
places  some  distance  from  railway  and  steamboat 
facilities.  The  cheese  is  usually  drawn  to  ship- 
ping places  by  patrons  of  the  factory.  In  many 
instances  the  wagons  used  are  not  fit  for  carrying 
cheese,  and  the  boxes  that  were  clean  and  neat 
become  dirty  or  broken  by  the  time  they  reach  the 


80 


FIG.    13 — A  CHEESE-BOX,  AS    IT   SHOULD  APPEAR 
WHEN   READY   FOR  SHIPMENT 

station.  The  cheese  should  be  drawn  in  clean, 
spring  wagons  and  should  be  placed  so  that  the  boxes 
do  not  roll  around  and  break.  Clean  straw  placed 
on  the  bottom  of  the  wagon-box  improves  the  con- 
ditions of  transportation.  A  covering  of  oiled  canvas 
placed  over  the  load  of  boxes  will  protect  them  from 
dust,  rain  and  the  heat  of  the  sun. 

HOW  TO  SELL  CHEESE 

When    cheese-factories    were    first    operated,    the 
cheese    was    purchased    by   buyers,    who    visited    the 


CARE,    SHIPMENT    AND    SALE    OF    CHEESE  /9 

factories  and  bought  the  cheese  on  its  merits.  Now 
most  cheese  is  sold  on  the  dairy  boards  of  trade. 
Large  dealers  send  representatives  to  each  cheese 
board  with  instructions  to  buy  cheese  at  a  certain 
price.  Usually  there  is  enough  competition  be- 
tween buyers  to  insure  the  full  market  prices. 
Buyers  are  allowed  by  their  employer  one-six- 
teenth to  one-eighth  cent  per  pound  for  buying 
cheese,  and  very  often,  in  the  heat  of  competition, 
they  pay  the  cheese  seller  this  commission  in  order 
to  secure  the  cheese.  This  is  not  objectionable, 
if  it  does  not  continue  too  long.  If  the  buyer  re- 
ceives no  pay  for  his  work,  he  frequently  finds  fault 
with  or  rejects  the  cheese  and  asks  for  a  reclaim  of 
a  few  dollars  from  the  cheese-maker,  when  other- 
wise the  cheese  would  pass  inspection.  In  sections 
where  cheese  is  inspected  in  the  factories,  the  cheese- 
board  method  is  fairly  satisfactory,  but  when  the 
cheese  has  to  be  sent  to  a  distant  center  of  inspec- 
tion, there  is  continual  complaining  by  either  buyer 
or  seller. 

METHOD    OF   PAYING    FOR    CHEESE 

With  few  exceptions,  cheese  is  now  shipped  to 
the  order  of  some  bank.  After  the  buyer  has  in- 
spected and  accepted  the  cheese,  he  gives  the  seller 
a  draft  of  his  firm  on  the  local  bank  for  the  value 
of  the  cheese.  The  bank  then  draws  on  the  firm 
and  the  cheese  belongs  to  the  bank  till  the  draft 
is  honored.  This  method  is  a  real  cash  business 
and  protects  the  factoryman  from  losses  caused  by 
fraudulent  practices  of  dishonest  cheese  merchants. 


CHAPTER  VIII 

Commercial  Qualities  of  Cheddar  Cheese 
and  Methods  of  Judging 

In  commercial  transactions  in  cheese,  certain 
points  or  qualities  have  been  adopted  as  a  basis 
or  standard  in  judging  the  commercial  value  of  this 
product.  The  terms  used  in  expressing  the  different 
qualities  vary  considerably  in  different  market  cen- 
ters, and  the  same  expression  is  used  with  different 
meanings  by  different  persons.  Frequently  indi- 
viduals use  terms  that  are  strictly  local  or  per- 
sonal. It  is  desirable  that  there  should  be  a 
uniform  usage  and  a  common  understanding  in  re- 
spect to  the  terms  used  in  judging  cheese.  The 
attempt  is  made  here  to  discuss  the  terms  in  com- 
mon use  and  to  define  them  as  well  as  may  be,  in 
the  hope  that  it  may  serve  as  an  aid  in  bringing 
about  a  general  agreement  in  respect  to  the  use 
and  understanding  of  the  expressions  employed 
in  judging  and  scoring  cheese.  The  definitions 
here  given  can  hardly  be  expected  to  be  in  full  agree- 
ment with  the  usage  of  everyone,  since  individuals 
differ  from  one  another  so  much  in  their  use  of  these 
terms. 

SAMPLING  AND  TESTING  CHEESE 

In  testing  its  commercial  qualities,  a  sample  of 
the  cheese  to  be  examined  is  obtained  by  means 

80 


JUDGING   COMMERCIAL    QUALITIES  8l 

of  a  cheese-trier.  This  is  inserted  nearly  its  whole 
length,  if  possible,  into  the  cheese,  turned  around 
once  and  then  drawn  out,  bringing  with  it,  as  the 
sample,  a  long,  round  cylinder,  commonly  called 
"plug." 

The  plug  should  always  be  drawn  from  the  top 
and  not  from  the  side,  in  order  to  avoid  injuring  the 
protective  power  of  the  bandage.  The  plug  drawn 
is  examined  by  smelling,  feeling,  appearance,  etc., 
in  reference  to  the  various  qualities  mentioned 
below. 

TERMS  USED  IN  DESCRIBING  QUALITIES 
OF   CHEESE 

The  following  qualities  have  been  selected  to  serve 
as  a  basis  in  the  commercial  testing  and  scoring  of 
cheese:  (i)  Flavor,  (2)  texture,  (3)  body,  (4)  color, 
(5)  .salt,  and  (6)  appearance. 

Flavor. — By  flavor  is  meant  the  quality  that  is 
perceptible  to  the  smell  and  taste.  The  sense  of 
smell  is  depended  upon  in  testing  flavor  in  cheese 
much  more  -largely  than  is  the  sense  of  taste,  because, 
in  examining  a  large  number  .of  samples  of  cheese 
in  succession,  constant  tasting  soon  dulls  not  only 
the  sense  of  taste  but  also  that  of  smell.  Flavor  in 
cheese  is  due  to  the  formation  of  some  unknown 
compound  or  compounds  during  the  ripening  process 

(P-  375)- 

Testing  flavor  in  cheese. — The  flavor  is  best  ob- 
tained by  direct  smelling  of  the  plug  as  soon  as  it  is 
drawn  and,  in  addition,  by  crushing  and  warming 
some  of  the  cheese  between  the  thumb  and  fingers 
and  then  smelling. 


82        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

Terms  used  in  describing  cheese  flavor. — From 
a  great  variety  of  names  applied  to  various  flavors 
found  in  cheese,  the  following  terms  are  selected 
for  consideration:  (i)  Perfect,  (2)  high  or  quick, 
(3)  clean,  (4)  low  or  flat,  (5)  strong,  (6)  too 
much  acid,  (7)  too  little  acid,  (8)  sour,  (9)  sweet 
or  fruity,  (10)  rancid,  (n)  tallowy,  (12)  tainted, 
(13)  stable,  (14)  weedy,  (15)  bitter,  (16)  cowy, 
(17)  fishy,  (18)  hydrogen  sulphid. 

(1)  Perfect  flavor  applies  to  cheese  when  it  some- 
what resembles  that  of  first-class  butter  with  an  added 
quality  of  its  own  that  is  characteristic  but  cannot  be 
described    further   than   to    call    it   cheese-like.     It   is 
sometimes  described  as  "nutty."     This  flavor   should 
be  marked,  but  not  strong.       It  should  be  free  from 
all  other  flavors,  particularly  the  more  or  less  offen- 
sive products  of  undesirable  fermentations.     The  taste 
should  be  mild  and  somewhat  lasting,  but  should  not 
be  so  sharp  as  to  "bite"  the  tongue. 

(2)  High  or  quick  flavor  is  a  delicate  flavor  that 
disappears  quickly. 

(3)  Clean  flavor  is  free  from  every  trace  of  un- 
pleasant aroma  or  taste. 

(4)  Low  or  flat  flavor  applies  to  slight  traces,  or 
absence,  of  flavor;    it  is  insipid. 

(5)  Strong  flavor  is  a  good  flavor  very  pronounced 
but  free  from  everything  offensive ;   it  is  a  good  flavor 
strongly  developed. 

(6)  Too  much  acid  applies  to   flavor  that  smells 
somewhat  sour,  but  does  not  taste  sour. 

(7)  Too  little  acid  applies  to  a  mild  flavor,  lacking 
in  character. 


JUDGING  COMMERCIAL    QUALITIES  83 

(8)  Sour  flavor  is  characterized  by  a  sour  taste 
when  the  cheese  is  fresh,  owing  to  the  presence  of 
too  much  whey. 

(9)  Sweet  or  fruity  flavor  is  suggestive  of  artificial 
pineapple  odor  and  is  somewhat  "sickish"  to  taste. 

(10)  Rancid  flavor  is  that  of  butyric  acid,  more 
common   in   old   cheese  than   in   young.     When   very 
strong,  it  affects  a  delicate  throat  with  a  slight  sensa- 
tion of  choking  or  strangling. 

(n)      Talloivy  flavor  is  like  that  of  tallow. 

(12)  Tainted  flavor  includes  a  variety  of  odors, 
mildly  to  strongly  offensive. 

(13)  Stable  flavor  suggests  the  smell  of  cow  ma- 
nure. 

(14)  Weedy    flavor    applies    to    such    abnormal 
flavors   as   come   from   onions,   leeks,   cabbages,   rag- 
weed, etc. 

(15)  Bitter  flavor  is  self-descriptive.     It  is  often 
due   to   certain    fermentations    that    develop    when    a 
cheese  is  undersalted. 

(16)  Cowy  flavor  is  suggestive  of  the  breath  of  a 
cow  and  may  develop  in  cheese  from  some  form  of  a 
fermentation. 

.(17)  Fishy  flavor  is  self-descriptive.  It  is  caused 
by  certain  ferments  that  are  present  in  milk. 

(18)  Hydrogen  sulphid  is  a  gas  which  gives  the 
odor  that  is  characteristic  of  the  water  of  sulphur- 
springs.  It  is  found  in  cheese  ripened  at  high  tem- 
perature. The  odor  is  rarely,  if  ever,  as  strong  as  in 
the  water  of  a  sulphur-spring.  A  cheese  with  this 
flavor,  or  a  fishy  flavor,  is  technically  known  as  a 
"stinker."  The  presence  of  this  gas  can  be  detected 
by  holding  a  bright  silver  coin  against  the  cheese-plug 


84        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


FIG.        14 — CHARACTERISTIC       AP- 
PEARANCE   OF    A    CLOSE-TEX- 
TURED   CHEESE 


"body"  as  a  part  of 
the  texture,  but  the 
two  qualities  are 
clearly  distinct  and 
should  not  be  con- 
fused. 

Testing  texture  in 
cheese. — The  texture 
of  cheese  is  tested 
by  an  examination  of 
the  plug  with  refer- 
ence to  the  presence 
of  holes.  The  plug 
is  broken  in  two  and 


for  a  moment ;  the  sil- 
ver tarnishes  if  any  ap- 
preciable amount  of 
hydrogen  sulphid  is 
present. 

Texture.  L—  Texture, 
as  applied  to  cheese, 
refers  chiefly  to  com- 
pactness or  appearance 
of  solidity.  It  is  quite 
common,  unfortunate- 
ly, to  regard  the 


FIG. 


16 — TYPICAL  TEXTURE  OF  SWEET- 
CURD  CHEESE 


FIG.  15 — CHARACTERISTIC  APPEAR- 
ANCE OF  A  LOOSE  OR  POROUS. 
TEXTURE 


the  broken  ends 
examined  for  the 
characte  ristic 
flinty  appearance. 

Terms  describ- 
ing t  e  x  t  u  r  e. — 
T  h  e  following 
terms  are  among 


JUDGING  COMMERCIAL    QUALITIES 


those  most  commonly  used  in  describing  texture: 
(i)  Perfect,  (2)  close,  (3)  loose,  (4)  mechanical 
holes>  (5)  gas  or  pin-holes,  (6)  Swiss-holes. 


FIG.    17 — EFFECTS  OF  GASSY   FERMENTATION  IN  CHEESE 

(i)  Perfect  texture  in  cheese  is  shown  when  a 
plug  or  a  cut  surface  of  the  inside  of  the  cheese 
presents  to  the  eye  a  solid,  compact,  continuous 
appearance,  free  from  breaks,  holes  and  chunks. 


FIG.    18 MECHANICAL  HOLES    IN    CHEESE    NOT    PERFECTLY 

CEMENTED 


86        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

When  a  plug  is  broken  in  two,  it  should  show  a  flaky 
appearance,  termed  a  "flinty"  break,  resembling  the 
surface  of  broken  flint  or  steel. 

(2)  Close  texture   describes   the   appearance  of  a 
cut  surface  of  cheese  when  free  from  all  kinds  of  holes. 
Such    cheese    is    often    described    as    "close-boring." 
(Fig.   14.) 

(3)  Loose  or  porous  texture  is  indicated  by  lack 
of    solid    compactness,    being    more    or    less    full    of 

holes,  which  vary  from 
a  few  (Figs.  15  and  16) 
to  enough  to  make  a 
spongy  (Fig.  17)  ap- 
pearance. One  variety 
is  known  as  fish-eye, 
due  to  action  of  yeasts 

(4)  Mechanical  holes 
in  cheese  are  irregu- 
lar, open  spaces, 

FIG.  19— SWISS-HOLES  caused    by    the    incom- 

plete   cementing   of   the 
pieces  of  curd  in  the  press.     (Fig.  18.) 

(5)  Gas-holes  or  pin-holes  are  small  holes,  pro- 
duced by  gaseous  products  of  fermentation. 

(6)  Swiss-holes  are  fairly  large,  round  holes,  such 
as  are  present  in  Emnienthaler  cheese.     (Fig.  19.) 

Body. — This  term,  used  in  connection  with  cheese, 
refers  to  the  consistency,  firmness  or  substance  of 
cheese.  It  is  largely  influenced  by  the  amount  of  fat 
and  moisture  in  cheese. 


JUDGING   COMMERCIAL  QUALITIES  87 

Testing  body. — This  quality  is  found  by  pressing 
a  piece  of  cheese  between  the  thumb  and  fingers. 

Terms  describing  body. — The  following  terms  are 
among  those  used  in  describing  the  body  of  cheese: 
(i)  Perfect,  (2)  solid  or  firm,  (3)  smooth,  (4)  silky, 
(5)  waxy,  (6)  pasty  or  salvy,  (7)  stiff,  corky  or 
curdy,  (8)  weak-bodied,  (9)  mealy,  (10)  gritty,  (n) 
watery,  (12)  over  dry. 

(1)  Perfect  body  in  cheese  is  indicated  when   it 
feels    solid,    firm   and    smooth    in    its    consistency   or 
substance.     It  does  not  crumble  under  pressure.     A 
plug   drawn   from   a   cheese   of   perfect   body  should 
be  smooth  in  appearance  and  not  "fuzzy." 

(2)  Solid,  firm  or  meaty  body  is  indicated  when 
cheese  offers   a  certain  amount  of  resistance  under 
pressure,  somewhat  like  that  shown  by  a  piece  of  fat 
pork  or  cold  butter.     The  term  meaty  is  also  used. 

(3)  Smooth-bodied  cheese,  when  pressed  between 
the  thumb  and  fingers,  feels  smooth  and  velvet-like, 
as  distinct  from  harsh,  gritty  or  mealy. 

(4)  Silky-bodied  cheese  is  smooth  in  feeling  but 
not  oversolid  in  consistency. 

(5)  Waxy-bodied    cheese    is    much    the    same    as 
silky,  but  possessing  more  firmness  or  solidity. 

(6)  Pasty   or  salvy  cheese   is   very   soft,   usually 
from  an  excess  of  moisture.     When  pressed,  it  sticks 
to  the  fingers. 

(7)  Stiff,  corky  or  curdy  cheese  is  hard,  tough, 
overfirm ;  it  does  not  crush  down  readily  when  pressed 
in  the  hand. 

(8)  Weak-bodied  cheese  is  very  soft,  lacking  in 
firmness,     but     not     necessarily     sticky     like     pasty 
cheese. 


88        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

(9)  Mealy  or  crumbly  cheese  breaks  down  in  fine 
crumbs  when  pressed. 

(10)  Gritty-bodied  cheese    feels   harsh  and  gritty 
under  pressure. 

(n)  Watery-bodied  cheese  is  excessively  soft, 
pasty  and  sticky. 

(12)  In  an  over  dry  cheese  the  body  is  very  hard 
or  mealy. 

Color. — The  color  of  cheese  varies  considerably, 
whether  artificially  colored  or  not.  There  appears 
to  be  an  increasing-  demand  for  nncolored  cheese. 
The  coloring  varies  from  a  pale  yellow  to  a  red- 
dish yellow,  according  to  the  demands  of  special 
markets. 

Testing  color. — The  color  is  tested  by  inspection 
with  the  eye,  the  examiner  noticing  particularly 
unevenness  and  any  extreme  condition  of  color. 

Terms  describing  color. — Color  in  cheese  is  de- 
scribed in  the  following  terms:  (i)  Perfect,  (2) 
straight,  (3)  translucent,  (4)  white  specks,  (5) 
streaked,  (6)  wavy,  (7)  mottled,  (8)  acid-cut,  (9) 
high,  (10)  light,  (n)  uncolored. 

(r)  Perfect  color  in  cheese  is  indicated  by  even- 
ness of  color  throughout  the  mass.  A  plug  held 
between  the  eye  and  light  should  appear  somewhat 
translucent. 

(2)  Straight    color    is    an    even,    uniform    color 
through  the  whole  cheese. 

(3)  Translucent  applies  to  color  in  cheese  which 
appears   slightly  translucent   when  the   plug   is   held 
between  the  eye  and  the  light. 

(4)  White  specks  is  a  term  that  describes  itself. 
Such    specks    in    cheese    are    a    defect.      They    may 


JUDGING   COMMERCIAL    QUALITIES  89 

appear    in     cheese    cured     at    low    temperature     (p. 

332). 

(5)  Streaked  color  indicates  that  there  are  light- 
colored  portions  in  the  form  of  streaks. 

(6)  Wavy  color  applies  to  lighter  portions  appear- 
ing in  the  form  of  waves. 

(7)  Mottled    color    shows    in    cheese    in    lighter- 
colored    spots    of    fairly    large    size,    more    or    less 
irregular. 

(8)  Seamy  color  applies  to  the  appearance  of  a 
pale  rim  surrounding  each  piece  of  curd  and  showing 
the  outline  of  the  pieces  as  they  were  before  being 
pressed  (p.  131). 

(9)  Acid-cut  color  is  shown  in  cheese  when  con- 
siderable   portions    of    the    cheese    have    been    made 
lighter   in   color   by  the   presence   of   too    much   acid 
(  whey). 

(10)  High  color  is  indicated  by  a  reddish  color, 
caused   by   using   too    much    coloring-matter.     How- 
ever, the  question  of  color  is  a  relative  one,  because 
the  demand  in  different  markets  varies  from  uncolored 
to  extremely  high  color. 

(u)  Light  color  is  the  term  usually  used  in  de- 
scribing cheese  that  has  been  made  uniformly  dead 
white  by  the  action  of  too  much  acid  (whey). 

(12)  Red  spots  are  places,  usually  small  in  area, 
having    somewhat    the    appearance    of    iron-rust    (p. 

131). 

(13)  Uncolored  cheddar  cheese  is  not  white,  but  of 
a  light  amber  shade. 

Salt. — The  amount  of  salt  in  cheese  varies  some- 
what with  different  markets.  There  is  seldom 
experienced  difficulty  of  uneven  salting  in  cheese, 


90        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

because  the  salt  slowly  permeates  the  cheese  in  the 
ripening  process.  Little  variations  usually  occur  in 
different  parts  of  the  same  cheese,  but  are  so  slight 
as  to  be  incapable  of  being  noticed  by  ordinary 
methods  of  examination. 

Testing  cheese  for  salt. — The  quality  of  cheese 
as  influenced  by  the  salt  is  found  simply  by 
tasting. 

Terms  used  in  describing  salt. — In  describing 
the  relation  of  salt  to  cheese,  the  following  terms 
are  used:  (i)  Perfect,  (2)  too  much,  (3)  too 
little. 

(1)  Perfect  applies   to   salt   in   cheese  when   just 
enough    has   been    used   to    impart   a    sufficient   taste 
of  salt. 

(2)  Too  much  salt  is  indicated  by  salty  taste.     Too 
much  salt  in  cheese  causes  a  dry,  mealy,  overfirm  body 
and  imperfect  flavor. 

(3)  Too  little  salt  is  shown  by  insipidity  of  taste. 
It  is  usually  accompanied  by  bitter  flavor  and  porous 
texture. 

Appearance. — This  term  refers  to  the  general 
appearance  of  the  cheese  to  the  eye  in  respect  to 
uniformity,  neatness  and  cleanliness.  It  may  also 
include  the  boxing.  One  system,  as  in  the  case  of 
butter,  describes  under  "finish"  the  appearance  of  the 
cheese,  and  under  "packages"  the  boxing;  and  we 
will  follow  this  method  here. 

Testing  appearance. — When  the  cover  of  the  box 
is  removed  for  sampling,  in  the  case  of  boxed 
cheese,  the  appearance  of  the  cheese  is  noticed  and 
the  box  itself  is  examined.  Cleanliness  and  neat- 


JUDGING    COMMERCIAL   QUALITIES  9! 

nesu   are   the   points   to   observe    in   judging   appear- 
ance. 

Terms  describing  appearance. — The  general  terms 
used  in  describing  appearance  are  (i)  finish  and  (2) 
package. 

(1)  Finish  in  appearance,  in  order  to  be  perfect, 
mu^t    meet    the    following    requirements :     The    rind 
mur.t    be    smooth,    even    in    color,    free    from    cracks 
and    fairly    hard.        The    bandage    must    be    without 
wrinkles  and  must  be  neatly  rounded  over  the  edges 
about  an  inch  on  each  end  of  the  cheese.     The  sides 
of    the    cheese    should    be    straight    and    of    uniform 
height  all  around. 

The  faults  of  appearance  in  finish  are  as  fol- 
lows, the  terms  being  self-descriptive :  ( i )  Cracks, 
(2)  light  spots,  (3)  roughness  in  rind,  (4)  uneven 
edges,  (5)  wrinkles  in  bandage,  (6)  lack  of  uni- 
formity in  ends  and  in  height,  (7)  bulging  out  at 
sides  or  ends. 

(2)  Package. — The    packages    or    boxes    are    re- 
garded as  perfect  when  of  good  material,  well  made, 
strong,    clean,    close-fitting,    uniform    in    size    and    in 
undamaged   condition. 

JUDGING  AND  SCORING  CHEESE 

The  qualities  described  in  the  preceding  pages 
are  used  for  judging  and  fixing  the  commercial 
value  of  cheese.  Judging  cheese  consists  in  making 
an  examination  of  a  cheese  with  reference  to  the 
various  points  of  quality,  which  have  been,  de- 
scribed in  the  foregoing  pages,  as  a  basis  for  scor- 
ing cheese,  which  consists  in  assigning  to  each 


92         SCIENCE  AND   PRACTICE   OF   CHEESE-MAKING 


quality  a  definite  value,  corresponding  to  its  char- 
acter as  found  in  the  cheese  examined.  In  judging 
cheese  one  must  have  in  mind  ( I )  the  perfection 
of  quality  in  each  case  as  a  basis  for  comparison, 
and  (2)  the  proper  perspective  of  the  different 
qualities  in  relation  to  each  other. 

Scale  of  points. — To  each  quality  is  assigned  a 
definite  numerical  value  and  these  numbers  are  called 
a  scale  of  points.  The  different  values  assigned  to 
the  various  qualities  indicate  perfection  in  each 
case  and  the  totals  aggregate  100.  Slightly  differ- 
ent values  are  assigned  in  different  cheese  markets 
and  for  cheese  made  by  different  variations  in  the 
process  of  manufacture.  Below  we  present  ex- 
amples of  different  types  of  scale  of  points: 


Export  cheese 

Home-trade  cheese 

English  market 

Flavor  
Texture  
Body 

45 
15 
15 

50 
{25 

35 
15 
25  (quality) 

Color  

15 

15 

Appearance  
(Finish) 

10 

10 

10  (make) 

In  the  case  of  home-trade  cheese,  a  larger  num- 
ber of  points  is  allowed  for  perfect  flavor,  because 
such  cheese,  on  account  of  its  high  water-content, 
easily  develops  poor  flavor  and,  consequently, 
flavor  deserves  more  attention  in  judging  and 
scoring  than  in  case  of  export  cheese,  which,  with 
smaller  water-content,  is  more  uniform  in  flavor. 
Then,  again,  in  home-trade  cheese,  closeness  of 
texture  is  not  regarded  as  highly  essential,  the  main 
emphasis  being  given  to  body. 


FUDGING  COMMERCIAL  QUALITIES  93 

In  explanation  of  the  English  scale  of  points,  it 
may  be  stated  that  the  majority  of  Englishmen  pre- 
fer cheese  of  considerable  age,  properly  ripened  and 
rather  sharp  in  taste,  and  it  is  this  character  which 
they  express  by  the  word  "quality." 

Method  of  scoring. — In  scoring  a  sample  of 
cheese,  an  examination  is  made  with  reference  to 
each  of  the  qualities  mentioned.  In  those  qualities 
in  which  it  is  perfect,  it  is  given  the  values  or 
points  assigned  above.  If  the  cheese  is  defective 
in  any  quality,  that  is,  short  of  perfect,  then  a 
smaller  value  is  given  than  the  one  indicated  above 
in  the  scale  of  points ;  the  more  defective  the  cheese 
is  in  any  quality,  the  lower  is  the  value  or  number 
of  points  given  it.  When  all  the  qualities  have  been 
scored,  the  numbers  of  points  assigned  to  them  are 
added  and  the  total  is  the  score  of  the  cheese  under 
examination. 

It  can  readily  be  seen  that  judgment,  trained  by 
experience,  is  required  to  assign  to  each  quality  its 
proper  number  of  points.  The  sense  of  smell  and  of 
taste  must  be  highly  developed  by  training  in  the  field 
of  experience.  The  eye  and  touch  must  also  be 
trained  by  special  experience  in  the  actual  work  of 
sampling,  studying  and  judging  cheese. 

Score-cards. — For  convenience,  score-cards  are 
used  in  keeping  records  of  the  results  of  scoring 
where  many  samples  are  examined.  The  following 
form  (see  next  page)  illustrates  a  commercial  score- 
card. 

In  commercial  scoring,  reasons  for  the  number 
of  points  given  are  nbt  stated ;  but  in  dairy  schools 
and  competitive  public  exhibitions,  where  educa- 
tional purposes  are  in  view,  the  reason  for  each 


94        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


Name  or  number  identifying  sample  .  .  . 
Class  or  kind  of  cheese 


Date. 


Judge 


QUALITY 

Score-points 

Sample 
1 

Sample 
2 

Sample 

Sample 

Flavor  
Texture 

45 
15 

42 
14 

40 
13 

36 
12 

35 
10 

Body  
Color 

15 
15 

14 
15 

15 
14 

12 
13 

10 
12 

Appearance  

10 

10 

8 

10 

8 

95 

90 

83 

75 

score  should  be  given.  The  educational  feature 
should  be  made  especially  prominent  at  country 
and  state  agricultural  fairs,  at  conventions  of  dairy- 
men's associations,  etc.  There  is,  and  has  been, 
altogether  too  little  attention  given  to  the  educa- 
tional feature ;  the  main,  and  usually  the  sole,  pur- 
pose has  been  to  capture  prizes.  Such  occasions 
can  be  made  extremely  valuable  in  an  educational 
way  by  indicating  in  detail  the  defects  and  then 
indicating  how  these  may  be  overcome.  The  follow- 
ing form  of  score-card  for  such  purposes  is  a  sugges- 
tion, which  may  be  modified  to  suit  any  special 
conditions : 

EDUCATIONAL   CHEESE-SCORING   CARD 

Judge 


Date 

.Class 

Name  or  number  identifying  cheese 


NUMERICAL  SCORE 

Qualities  :              Flavor 
Points  for       {          AC 
Perfection  :      f 

Score  given  • 

Texture           Body           Color 
15                 15                15 

Appearance 
10 

Total  score 

JUDGING     COMMERCIAL    QUALITIES  95 

DESCRIPTIVE  SCORE  (Check  defects  in  list  below! 


Flavor 

Texture 

Body 

Color 

Appearance 

Perfect 

Perfect 

Perfect 

Perfect 

Perfect 

Clean       Quick 

Close 

Firm 

Straight 

Finish: 

Perfect 

Flat         Strong 

Porous 

Smooth 

Translucent 

Cracks, 

Light  spots 

Too  much  acid 
Too  little  acid 

Mechanical-holes 
Pin-holes 

Silky 
Waxy 

Light 
High 

Rough  rind 
Uneven  ends 

Sour         Bitter 

Swiss-holes 

Pasty 

Mottled 

Uneven  edges 

Cowy          Stable 
Sweet  or  fruity 
Weedy     Rancid 

Fish-eye-holes 

Weak-bodied 
Stiff  or  corky 
Crumbly 

Streaked 
Wavy 
White  specks 

Wrinkles 
Bulging 
Packages: 

Tallowy        Fishy 

Gritty 

Seamy 

Perfect 

Tainted 

Watery 

Acid-cut 

Clean   Dirty 

Hydrogen-sulphid 

Overdry 

Red  spots 
Uncolored 

Neat  Unif  'm 
Loose    Close 

Remarks 

Advice  for  overcoming  defects . 


Methods  of  grading  cheese. — The  classification 
of  cheese  according  to  the  results  of  judging  and 
scoring  varies  in  different  markets,  the  method  in 
each  case  being  arbitrary.  For  illustration,  one 
classification  is  into  (i)  "fancy,"  (2)  "firsts"  and  (3) 
"seconds."  In  the  Canadian  market,  there  are  first, 
second  and  third  grades. 

CHEESE-MAKERS    AND    JUDGING   CHEESE 

It  is  a  matter  of  regret  that  cheese-makers  do 
not  have  more  extended  practical  experience  in 
judging  cheese.  Every  cheese-maker  who  desires 
to  acquire  greater  efficiency  in  his  work  should 
own  a  good  cheese-trier  and  use  it  as  often  as 
practicable.  It  is  well  before  shipment  to  examine 
one  cheese  from  each  day's  make  and  then  study 


96       SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

the  results  in  connection  with  the  record  of  corre- 
sponding date,  giving  the  details  of  the  conditions 
of  manufacture.  This  is  frequently  impracticable, 
because  cheese  is-  shipped  before  it  can  be  properly 
judged.  Then,  again,  cheese  which  appears  well  when 
shipped  may  develop  imperfect  qualities  later ;  while 
some  cheese,  imperfect  at  the  start,  may  improve  later 
if  kept  under  proper  conditions. 


CHAPTER  IX 

Cheese-Factory  Construction 

A  cheese-factory  should  be  a  model  of  cleanliness 
in  every  dairy  community.  At  the  present  time  the 
word  cheese- factory  does  not  stand  for  any  such  ideal 
condition.  In  the  construction  or  remodeling  of  fac- 
tory buildings,  attention  should  be  given  to  the  follow- 
ing points:  (i)  Location  and  site,  (2)  material  to 
be  used,  (3)  architecture,  (4)  water-supply,  (5) 
drainage,  and  (6)  curing- rooms. 

LOCATION  AND  SITE 

The  selection  of  a  suitable  location  and  site  is  one 
of  the  most  important  factors  in  cheese-factory  con- 
struction. The  factory  should  be  centrally  located 
and,  if  possible,  on  a  hillside  where  advantage  may  be 
taken  of  gravity  and  other  natural  conditions. 

Before  we  were  familiar  with  the  importance  of 
sanitation,  cheese-factories  were  invariably  erected  on 
low,  wet  ground  where  a  water-supply  could  easily 
be  obtained.  No  attention  was  paid  to  the  means  of 
disposing  of  the  excess  of  whey  and  of  sewage  from 
the  building.  The  result  was  that  in  a  short  time  the 
soil  surrounding  the  factory  became  saturated  with 
decayed  waste  products ;  the  water-supply  was  made 
impure  from  the  same  source;  in  hot  weather,  flies 
gathered  in  large  numbers,  carrying  bacteria  and  dirt 

07 


98        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

from  the  stagnant  surroundings  into  the  vats  con- 
taining milk  and  curd.  As  a  result  of  these  condi- 
tions, bad  flavors  appeared  in  the  cheese,  and  cheese- 
makers  experienced  all  sorts  of  difficulties  in  the 
factory  operations.  Most  of  these  bad  conditions 
have  since  been  removed  or  remedied,  but  in  many 
parts  of  the  country  they  are  still  to  be  found.  In 
Ontario,  Canada,  especially,  great  improvement  has 
been  made  in  the  sanitation  of  cheese-factories  since 
the  passing  of  a  special  law  and  the  appointing  of 
special  sanitary  inspectors.  Most  factorymen  now 
appreciate  the  value  of  cleanly  conditions  surrounding 
the  entire  manufacturing  process,  but  many  must  be 
forced  to  put  their  buildings  and  equipment  in  proper 
condition. 

MATERIAL  TO  BE  USED 

Appearance,  cheapness,  durability  and  efficiency 
should  be  kept  in  mind.  Brick  buildings  are  to  be 
preferred,  and,  while  their  first  cost  is  greater  than 
wood,  they  are  the  most  durable  and  cheapest  in  the 
end.  Cement,  when  properly  made  and  used,  makes 
an  efficient,  fairly  cheap  and  durable  building.  Stone 
and  wood  are  commonly  used.  The  relative  economy 
with  which  the  building  material  can  be  obtained  will 
largely  influence  the  character  of  buildings  erected  in 
different  localities. 

ARCHITECTURE 

Plans  and  blue-prints  of  modern  cheese- factories 
are  always  available,  free  of  charge,  from  the  agricul- 
tural departments  of  the  different  governments,  so 


CHEESE-FACTORY    CONSTRUCTION  99 

that  it  is  unnecessary  in  this  treatment  of  the  subject 
to  go  into  details.  Suffice  it  to  say  that  the  architec- 
ture should  be  simple,  attractive  and  convenient.  The 
location  and  site  will  determine  to  a  great  extent  the 
style  of  architecture. 

WATER-SUPPLY 

Nothing  is  of  more  importance  in  factory  construc- 
tion than  the  water-supply.  The  quality  should  be 
pure  and  an  abundance  of  it  should  be  assured.  The 
purity  of  springs,  deep  wells,  rivers,  and  lakes  with 
a  large  outlet  can  usually  be  depended  upon,  but  the 
character  of  the  surrounding  area  drained  must  be 
considered.  Surface  water,  by  all  means,  should 
be  kept  out  of  the  wells.  If  milk  or  whey  enters  a 
well  accidentally  or  otherwise,  the  water  soon  becomes 
contaminated  and  unfit  for  use.  When  this  occurs, 
the  water  should  be  pumped  out  and  the  well  thor- 
oughly cleaned. 

DRAINAGE 

Drainage  is  so  closely  related  to  the  water-supply 
that  they  are  naturally  considered  together.  If  pos- 
sible in  any  way,  natural  drainage  should  be  secured. 
In  cheese-factory  work  there  is  usually  a  considerable 
volume  of  sewage,  consisting  of  wash  water  and 
excess  of  whey.  The  best  method  for  its  disposal 
is  now  attracting  the  attention  of  factorymen  and 
of  those  who  enforce  the  laws  of  health  and  sanita- 
tion. The  character  of  sewage  at  all  cheese-factories 
is  practically  the  same.  The  method  of  its  disposal 


IOO     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

will  depend  on  the  water  content,  the  character  of  the 
constituents,  and  slope  of  the  surrounding  soil.  The 
waste  or  superfluous  whey  is  the  main  cause  for  need 
of  improved  sanitation  at  cheese-factories.  If  it 
were  not  for  this,  the  wash  water  could  be  more 
easily  disposed  of.  However,  the  following  methods 
have  given  excellent  satisfaction  when  properly  in- 
stalled under  suitable  conditions. 

Removal  by  cartage. — This  system  requires  a 
storage-tank  for  wash  water  as  well  as  for  whey, 
although  many  factorymen  allow  the  wash  water  to 
run  into  the  whey-tank.  Arrangements  are  made  by 
which  some  person  agrees  to  remove  all  sewage  from 
the  factory  to  some  river,  lake  or  satisfactory  place 
of  disposal  and  to  clean  the  whey-vats  at  stated  times 
in  return  for  the  superfluous  whey  he  may  receive 
to  use  for  feeding  purposes.  As  a  rule,  this  method 
is  satisfactory,  and  its  use  is  advised  when  the  others 
are  not  more  practicable. 

Direct  disposal  into  large  lakes  and  running 
streams  of  water. — Many  factories  are  located  on 
the  banks  of  lakes  and  rivers,  into  which  it  'is  usually 
an  easy  matter  to  conduct  the  sewage  by  means  of 
piping  or  tile.  This  makes  an  ideal  method,  if  the 
body  of  water  is  large  or  has  sufficient  current  to 
carry  it  to  a  suitable  outlet. 

Septic-tank  system. — This  consists  of  a  series  of 
tanks,  in  which  the  sewage  is  treated  before  being 
allowed  to  flow  out  into  or  on  top  of  the  surrounding 
ground.  The  number  and  size  of  tanks  will  depend 
on  the  size  of  the  factory  and  the  character  of  soil 
into  which  the  treated  sewage  must  pass.  Fig.  20 
illustrates  a  plan  for  a  factory  with  a,  daily  capacity 


CHEESE-FACTORY 


for  10,000  pounds  of  milk,  whose  treated  sewage 
passes  out  into  heavy  soil  with  little  natural  drainage. 
The  material  used  in  tank  construction  can  be  iron, 
cement  or  wood.  Each  part  should  be  large  enough 
to  hold  the  sewage  of  24  hours.  By  this  arrangement 
the  sewage  is  in  the  tank  for  three  days.  At  the 
end  of  this  period  it  may  be  carried  by  piping  or  tile 
to  its  final  place  of  deposit.  The  overflow-pipes 
should  be  ventilated  to  prevent  siphoning  of  the  con- 
tents after  it  starts  to  overflow.  The  tanks  are 


f 


\  FROM  TACTORY                              2                                                               2 

\                      i                     .5 

\\                     i_                      «_ 

V 

r         I 

r          In 

SEWAGE 
OF                         > 

riRST  DAY                      g 

SEWAGE 
t                 SECOND 
5                       OAV 

SEWAGE 

=                   THIRD 
1                       OAV 

E 

1 

1 

\ 

1 

f 

' 

FIG.  20 SERIES    OF    SEPTIC    TANKS    CAPABLE    OF    HOLDING 

THREE    DAYS'    SEWAGE    FROM    A    CHEESE-FACTORY 
HANDLING   10,000  POUNDS  OF  MILK  A  DAY 

better  placed  under  ground  so  that  the  top  just 
reaches  the  surface.  It  should  have  a  good  top  and 
may  then  be  covered  with  earth.  It  is  advisable  to 
have  a  water-trap  in  the  pipe  delivering  the  sewage 
from  the  factory  to  the  septic  tank  in  order  to  pre- 
vent odors  returning.  This  system  is  very  efficient 
and  may  be  used  in  almost  any  locality.  In  some 
places  it  is  advisable  to  deposit  the  treated  sewage 
on  a  prepared,  gravel  filter-bed. 


I'KACTICE    OF    CHEESE-MAKING 


Cesspools.  —  When  the  surrounding  soil  is  of  sand 
or  gravel,  the  cesspool  makes  an  efficient  and  cheap 
method  for  sewage  disposal.  For  a  factory  with  a 
daily  capacity  of  10,000  pounds  of  milk,  a  cesspool  of 
the  following  dimensions  and  construction  is  ad- 
vised: A  hole  12  feet  in  diameter  and  6  feet  deep 
is  excavated.  This  should  be  lined  with  loose  stones 
up  to  within  one  foot  of  the  ground  surface.  Over 
this,  cedar  logs,  with  good  supports,  are  placed  at 
intervals  of  24  inches.  A  plank  covering  goes  over  the 
logs,  and  this  again  is  covered  with  earth,  making  the 


SLIDE    TRAP    DOOR    -"^ W/IRM  AIR 


SOLID     ICC 


CURING     ROOM 


.3= >COLD  AIR 


S- SHAPED    l"PIPE      FROM 
DRAIN    IN  ICE-HOUSE 

FIG.   21 — PLAN   SHOWING  SATISFACTORY   METHOD    FOR   SECUR- 
ING  CIRCULATION     OF    COLD  AIR     IN     CHEESE-CURING     ROOMS 

spot  unnoticeable.  A  cesspool  should  be  located  at 
least  20  feet  away  from  the  buildings,  and  on  the  lower 
side  of  the  source  of  water-supply.  The  pipe  lead- 
ing from  the  factory  floor  to  cesspool  should  have 
a  water-trap  to  prevent  returning  odors.  It  is  advis- 
able to  place  on  all  whey-tanks  an  overflow  pipe  con- 
nected with  the  drainage  deposit. 

CURING-ROOMS 

A   curing-room  should  be   so   constructed  that  the 
temperature  and  humidity  can  be  controlled.    It  should 


CHEESE-FACTORY    CONSTRUCTION 


103 


have  good  ventilation,  insulation  and  circulation  of 
pure  air.  Under  ordinary  conditions,  ice  provides 
the  cheapest  and  most  efficient  method  of  maintaining 
a  uniformly  cool  temperature  in  curing-rooms.  In 
large  cheese-making  centers,  artificial  refrigerating 
machines  are  used,  but  they  are  too  costly  for  ordinary 
cheese-factories.  Sub-earth  ducts  have  proved  unsatis- 
factory, since  they  are  too  often  least  efficient  when 
most  needed. 


DRAINAGE  DISPOSAL/^     \SEPTIC  TANKS  OR  CESS-POOL 

COAL  A. 
WOOD 

WHEY    TANKS 

STORE- 
ROOM 

'  "£± 

BOILER     ROOM 

iCf  HOUSE 

PRESS  

3 

STARTER 
ROOM 

0 

J 

1 

1                                                                 1      § 

VAT 

SINK& 
ROOM 

-r\ 

i  1  s 

VAT 

I       CURING         SHELVES                I     S 

1                                                              J     « 

VAT 

OFFICE: 

!                                                                 1     | 

1                                                                 1 

—  pREPS  = 

—  1 

FIG.  22 — MODERN   PLAN  SHOWING  IDEAL  ARRANGEMENT  OF 
CHEESE-FACTORY    ROOMS  AND    EQUIPMENT 

The  drawing  on  page  102  (Fig.  21)  provides  a 
scheme  by  which  the  air  in  the  curing-room  has  a 
continuous  circulation  over  a  bed  of  solid  ice 

The  curing-room  and  ice-house  should  have  good 
insulation  secured  by  the  use  of  lumber,  building- 
paper,  air-spaces,  shavings  and  cement  floors.  The 
ice-house  should  be  one-third  the  size  of  the  curing- 
room.  Three  thicknesses  of  lumber,  one  of  damp- 
proof  paper,  and  6  inches  of  shavings  provide 


IO4      SCIENCE   AND   PRACTICE    OF    CHEESE-MAKING 

sufficient  insulation  for  the  curing-room.  For  the  ic_- 
house  an  extra  thickness  of  lumber  and  damp-proof 
paper  is  advised  in  both  ceiling  and  wall  construction. 
The  ice-house  floor  and  walls  halfway  up  are  lined 
with  galvanized  iron. 

The  construction  of  the  floor  in  the  ice-house  is 
important,  as  provision  must  be  made  for  protecting 
the  ice  from  the  warm  temperatures  of  the  soil  under- 
neath. A  cement  floor  with  gravel  and  stone  support 
is  first  constructed.  Over  this,  2-inch  by  4-inch  sup- 
ports are  placed  on  edge  at  intervals  of  18  inches. 
Between  these  the  space  is  filled  with  coal  cinders 
or  shavings.  Over  this  a  2-inch  plank  floor  is  laid, 
and  this  covered  with  galvanized  iron.  A  drain  2 
inches  by  2  inches  should  .be  made  in  the  ice-house 
floor  close  to  the  curing-room  wall,  toward  which 
the  ice-house  floor  should  incline.  The  drain  is  neces- 
sary to  carry  off  the  water  from  the  melting  ice.  A 
close-fitting  S-shaped  pipe  with  water-trap  should 
connect  the  drain  with  outside  disposal.  Over  the 
galvanized  floor  is  placed  a  rack  made  of  2-inch  by 
4-inch  supports  on  edge.  This  prevents  the  ice  from 
lying  in  water  when  it  starts  to  melt.  During  the 
winter  months,  the  ice-house  is  packed  full  of  ice. 
No  sawdust  is  used,  the  insulation  being  sufficient  to 
protect  it 

As  Figure  21  shows,  small  trap-slides  are  placed 
near  the  ceiling  and  floor  between  ice-house  and  cur- 
ing-room. As  soon  as  these  are  opened,  the  warm  air 
in  the  curing-room  enters  the  openings  at  the  top, 
passes  over  the  ice  and  out  through  the  lower  openings, 
thus  creating  a  circulation  of  cold  air  through  the 
curing-room.  A  uniform  temperature  of  from  52° 


CHEESE-FACTORY    CONSTRUCTION 


105 


to  56°  F.  can  be  secured  throughout  the  entire  sum- 
mer season  in  this  way,  and  a  uniform  percentage  of 
moisture  is  also  assured 

When  this  system  is  not  used,  the  curing-room  air 
may  be  cooled  by  hanging  up  large  pans  filled  with 
ice,  but  the  moisture  from  them  generally  stimulates 
mold  formation.  Where  cold  running  water  is  avail- 
able, it  can  be  conducted  through  a  system  of  coil- 
pipes  around  the  walls  of  the  curing-room  and  the 
temperature  considerably  lowered. 


BOXING  AND  SHIPPING   SPACE 


CURING  ROOM 


26'x  »0' 


FIG.    23 — PLAN     FOR     CHEESE-FACTORY     HANDLING      12,000     TO 
20,000  POUNDS  OF  MILK  A   DAY. 


A— Boiler;  B— Engine;  0— Sterilizincr-oven ;  D— Weigh-can  and  scales;  E— Con- 
ductor-spout;  F— Bottle-rack ;  G— Milk-tester ;  H— Wash-sink ;  I— Cheese-vats ; 
J— Curd-sink ;  K— Steam -radiators;  L— Cheese-presses ;  M— Truck;  N— Curing- 
shelves. 

CHEESE-FACTORY  PLANS 

As  a  suggestion,  we  give  the  outline  of  a  plan  for 
cheese-factory  construction  with  special  reference  to 
convenience  of  arrangement  for  equipment.  (Fig. 

22.) 

We  give  also  an  outline  plan  published  by  U.  S. 
Baer,  of  Wisconsin.  (Fig.  23.) 


CHAPTER  X 

Cheese-Factory  Equipment 

A  cheese-factory  should  be  so  equipped  that  every- 
thing may  be  easily  kept  clean.  The  vats,  presses, 
sinks  and  all  utensils  should  be  placed  in  positions 
that  will  insure  convenience  and  a  minimum  amount 
of  labor.  Too  many  factories  at  the  present  time 
are  not  large  enough  for  the  equipment  they  contain, 
and  they  consequently  appear  untidy  and  dirty  to 
visitors  or  to  persons  inspecting  the  conditions  sur- 
rounding the  manufacturing  process.  Very  often,  too, 
the  utensils  are  not  clean  for  the  reason  that  the 
cheese-maker,  being  short  of  help,  neglects  part  of 
the  work.  Utensils  and  equipment,  properly  ar- 
ranged, will  save  a  great  many  steps  to  the  cheese- 
maker  in  a  day.  (Figs.  22  and  23.) 

Advice,  which  is  the  result  of  varied  experience  and 
which  is  often  of  considerable  help  to  persons  in  need 
of  such  assistance,  can  always  be  secured  from  ex- 
perts employed  by  the  different  departments  of  agri- 
culture. 

The  following  apparatus  is  sufficient  for  a  factory 
handling  10,000  pounds  'of  milk  daily. 

(1)  One    12-horse-power,    return-flue,    horizontal 
boiler  with  fixtures. 

(2)  Two  steam-heating  cheese- vats,  with  a  capac- 
ity of  7,000  pounds  each.     In  recent  years,  wood  suit- 
able for  making  cheese-vats  has  become  expensive  and 
hard  to  secure.     Many  manufacturers  are  using  wood 

106 


CHEESE-FACTORY    EQUIPMENT  IO7 

of  a  poorer  quality,  and  the  vats  are  not  durable. 
Steel  vats  have  been  placed  on  the  market  and  are 
giving"  general  satisfaction.  They  are  preferable  to 
the  average  wooden  vat  now  manufactured.  (Fig. 
24.) 

(3)  Whey-tank,  capacity  of  12,000  pounds.  If  the 
factory  is  so  located  that  its  elevation  permits  the  load- 
ing of  whey  without  pumping,  then  one  large  tank  can 
be  used.  However,  two  smaller  tanks  connected  by 
an  overflow-pipe  are*  preferable,  because,  when  one  is 
empty,  it  can  be  cleaned  while  the  other  contains  whey. 
Steel  tanks  are  preferable  to  wooden  or  cement  ones. 
They  neither  leak  nor  absorb,  are  easily  cleaned,  and 
are  more  durable.  Cement  tanks  are  not  durable, 


FIG.    24 — ONE    TYPE    OF    STEEL   CHEESE-VAT 

because   the   acid   and   salt   in   the   whey   destroy  the 
cement. 

(4)  One   6oo-pound,   double-beam   scale.      Scales 
are  in  daily  use  at  cheese-factories  and  it  is  advisable 
to  purchase  only  those  that  are  reliable  and  guaran- 
teed, such  as  the  "Fairbanks"  and  "Howe." 

(5)  One    7o-gallon    weighing-can    with    a    3-inch 
gate. 

(6)  One  milk-conductor  and  head. 

(7)  Apparatus  and  alkali  for  testing  acidity. 


108     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

(8)  One  Marschall  or  Monrad  rennet-test. 

(9)  One  3-8-inch,  horizontal,  steel  curd-knife. 

(10)  One     5-i6-inch     perpendicular,     wire     curd- 
knife. 

( 1 1 )  Two  small  solid-handle  dippers. 


(12) 

(13) 

(H) 
(15) 
able. 
(16) 


FIG.  25 — BARNARD'S  CURD-CUTTER 


One  strainer-dipper. 

Two  curd-agitators  of  McPherson  type. 

Two  curd-rakes. 

Two  thermometers,  strictly  correct  and  reli 

One  outfit  for  making  commercial  starters. 


FIG.  26 — GOSSELIN  CURD-MILL 

(17)  Two  whey-strainers  for  each  vat. 

(18)  One  large  knife  for  cutting  curd. 

(19)  One  curd-mill.       A  curd-mill   should  be   so 
constructed  that  its  knives  will  go  against  the  curd 


CH  EESE-F  A  CTOK  V    Eg  U I P  M  EN  T 


109 


in  cutting.  The  curd  should  not  be  pushed  against 
the  knives.  Such  mills  as  the  Barnard  (Fig.  25). 
Beech  and  Gosselin  (Fig.  26)  are  recommended. 
They  can  be  had  in  hand  or  steam-power. 

(20)  Two  curd-stirring   forks   of   wood   or   steel, 
with  points  turned  over  so  as  not  to  puncture  the  tin 
vats  during  stirring. 

(21)  One  curd-scoop. 

<  22)     One  flat-sided  curd-pail. 
(23)     Two  steel-frame,  automatic,  continuous-pres- 
sure gang-presses   with   hoops,    followers,   etc.,   com- 


FIG.  27 — CONTINUOUS-PRESSURE  GANG-PRESS 

plete.  (Figs.  27  and  28.)  Galvanized-steel  followers 
are  preferable  to  wooden  ones,  as  they  are  more  sani- 
tary, are  not  absorbent,  do  not  expand  or  contract 
readily,  and  are  more  durable.  Galvanized  rings 
are  preferable  to  the  fiber  or  rubber  ones  for  the  same 
reasons. 

(24)  One  24O-pound  cheese-scale. 

(25)  One  24-bottle  Babcock  milk-tester. 

(26)  Two  composite-sample     bottles    for    each 
patron,  < 


I1O     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

(27)  If  the   whey   is  to   be   separated   and   whey- 
butter  made  from  the  fat,  a  separator  and  machinery 
for  butter-making  will  be  necessary. 

(28)  An   instrument   for  determining  the  amount 
of  moisture   in   the   air  of   the   curing-room.        (Fig. 

29.) 

(29)  A  sterilizing-oven   for  sterilizing  milk  to  be 
used  in  the  preparation  of  starters  and  also  for  the 
sterilization  of  the  smaller   utensils   employed   in   the 
cheese-factory    will    be   found   convenient   and    highly 
useful.     Home-made  sterilizers  can  be  used  with  good 


FIG.  28 


FRASER     HOOP 


A— Complete  hoop;    B— Bandages; 
C— Follower ;  D— Fibrous  press-ring. 


WILSON    HOOP 

A— Complete  hoop ;  B— Bottom  cov- 
er with  wide  flange ;  C— Top  cover  with 
narrow  flange ;  1)— Closed  or  tight  hoop 
or  body;  E— Open  hoop  or  bandages. 


results.  A  galvanized-iron  box,  double-jacketed,  is 
arranged  to  admit  steam  between  the  walls.  An  open- 
ing in  the  top  of  the  outside  wall  is  arranged  to  regu- 
late steam  pressure  and  another  at  the  bottom  to  carry 
off  condensed  water.  The  outside  may  be  protected 
by  a  covering  of  asbestos  or  other  boards. 
(30)  One  Ouevenne  lactometer. 

FACTORY  FURNISHINGS 

Fuel,  coal  or  wood. 

Rennet-extract  (Hansen's  is  recommended). 


CHEESE-FACTORY    EQUIPMENT 

Cheese  color  (Hansen's  is  recommended). 

Commercial  starter. 

Vat-brooms. 

Floor-brush. 

Washing-powder. 

Cotton  for  press-cloths. 


ill 


FIG.  29 — APPARATUS     FOR    INDICATING 

PERCENTAGE  OF  MOISTURE  IN  AIR 

OF  CURING-ROOM 


Cheese-bandage.  This  should  be  seamless  and  the 
size  34  inch  smaller  than  the  diameter  of  hoops;  a 
cheese  retains  its  shape  better  with  such  bandage. 

Cheese-circles. 

Cheese-salt.  Paper-lined  barrels  are  preferable. 
The  salt  should  be  regular  cheese-salt.  Fine  butter- 
salt  dissolves  too  rapidly  and  does  not  penetrate  the 


112     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

curd  so  well.  Such  brands  as  Windsor,  Diamond, 
Crystal,  Genesee,  LeRoy,  Warsaw  and  Worcester  arc 
generally  reliable. 

Cheese-boxes.  These  are  made  of  both  wood  and 
paper.  If  properly  made,  either  material  is  satisfac- 
tory. The  boxes  should  be  strong  enough  to  stand 
handling  in  shipping,  and  they  should  fit  the  cheese. 
One-quarter  inch  between  the  cheese  and  box  is  suf- 
ficient. 

Scale-boards. 

Milk-sheets. 

Blanks  for  records  of  conditions  of  cheese-making 
(p.  16). 

Blanks  for  reports  to  patrons. 

Milk-record  books. 

Cheese-shipping  books. 

Materials  and  stencils  for  branding  boxes. 

It  is  a  great  mistake  for  factorymen  to  purchase 
cheap  furnishings  just  because  they  are  cheap.  Cheese 
of  the  best  quality  is  the  most  profitable  to  make,  and 
no  cheese-maker  can  afford  to  use  poor  furnishings  if 
he  expects  to  have  his  cheese  of  finest  quality  and 
appearance. 


Part  II 

Defects  of  American  Cheddar 
Cheese  in  Flavor,  Body,  Tex- 
ture,  Color  and   Finish: 


Causes 

Remedies 

Means  of  Prevention 


CHAPTER  XI 

Defects  in  Flavor 

In  this  and  several  chapters  following,  an  effort 
is  made  for  the  first  time  to  present  in  systematic 
form  a  discussion  of  the  imperfections  that  are  most 
commonly  found  in  our  American  cheddar  cheese. 
The  need  of  this  requires  no  explanation,  and  the 
importance  of  the  subject  is  only  too  obvious.  The 
extent  of  defects  in  our  cheese  is  well  known  and 
also  their  demoralizing  effect  upon  the  industry.  In 
reality,  the  whole  aim  of  the  cheese-maker  is,  of 
course,  to  produce  cheese  free  from  imperfections. 
In  discussing  the  subject,  it  is  necessary  to  know  (i) 
what  the  defects  are,  and  (2)  to  what  causes  they 
are  due.  We  are  then  in  position  to  consider  remedies 
and  means  of  prevention.  The  subject  will  be  pre- 
sented under  the  following  divisions: 

Defects  in 

(1)  Flavor. 

(2)  Body. 

(3)  Texture 

(4)  Color. 

(5)  Finish. 

In  each  division,  the  presentation  will  give  (i) 
description  of  defect,  (2)  causes,  (3)  methods  of  pre- 
vention and  (4)  remedies.  It  is  important  to  know 
how  to  prevent  the  recurrence  of  conditions  that  are 
responsible  for  cheese-making  troubles,  and  also  how 

115 


Il6      SCIENCE   AND  PRACTICE   OF    CHEESE-MAKING 

to  handle  the  details  of  the  cheese-making  process 
when  the  presence  of  the  trouble  is  recognized.  The 
facts  will  be  presented  more  or  less  in  outline  form, 
in  order  to  make  reference  to  them  more  convenient. 

ACID  FLAVORS 

These  are  indicated  by  a  sour  smell  and  taste. 
Cause : 

(1)  Over-development    of   acidity   during  the   process  of 

cheese-making,  which  is  commonly  due  to — 

(a)  Ripening  the    milk    too    much    before    adding 
the  rennet. 

(b)  The  use  of  too  much  starter. 

(c)  Failure  to  firm  the  curd  sufficiently  before  re- 
moving the  whey. 

(2)  Any  condition  that  retains  in  the  curd  and  cheese  an 
excessive  amount  of  whey  (p.  46). 

Prevention : 

(1)  Have  less  acidity  in  the  milk  before  adding  rennet- 

extract.  Sour  milk,  or  milk  over  0.26  per  cent  in 
acidity,  should  not  be  accepted  from  any  patron. 
High  acidity  can  be  overcome  by  patron,  if  he  will 
cool  milk  to  60°  F.,  or  better  50°  F.,  at  once  after 
milking. 

(2)  Use  less  starter.     Generally  i  to  2  per  cent  is  sufficient. 

(3)  Add  the  rennet  when  such  a    degree    of    acidity  is 

present  that  the  curd  will  become  firm  in  the  whey 
oefore  developing  the  desired  amount  of  acid. 

Remedy : 

(See  the  treatment  given  under  remedy  for  acid  body  (p.  122). 

OFF  FLAVORS 

These  are  flavors  that  are  not  clean,  such  as  rancid 
or  butyric  acid  flavor,  stable  or  cow-manure  flavor, 
fishy  flavor  and  hydrogen  sulphid  or  sulphur-spring- 
flavor.  When  these  develop  so  as  to  become  very 
strong,  they  are  called  "stinkers." 


DEFECTS   IN   FLAVOR 


Cause: 

Undesirable  bacteria,  which  gain  entrance  to  the  milk  or 
to  the  curd,  commonly  due  to  — 

(1)  Failure  of  patrons  thoroughly  to  wash  and  scald  all 

cans  and  utensils  coming  in  contact  with  the  milk. 
This  is  particularly  true  of  cans  in  which  whey  is 
carried  from  the  factory. 

(2)  Careless  milking  in  unclean  places. 

(3)  Allowing  the  milk  to  become  exposed,  after  milking, 

in  places  where  the  air  is  impure. 

(4)  Keeping  the  milk  at  too  high  temperature. 

(5)  Using  an  unclean  strainer  at  either  the  farm  or  cheese- 

factory. 

(6)  Using   utensils   in   the    factory  that   have   not    been 

thoroughly  cleaned  and  scalded. 

(7)  Using  badly-flavored  starters. 

(8)  Using  impure  water  for  diluting  rennet. 

(9)  Soaking  curd  in  impure  water  after  milling. 

(10)  Using  tainted  rennet  or  salt. 

(11)  Ripening  cheese  at  temperatures  above  65°  F. 
Prevention  : 

Strict  cleanliness  in  the  production  and  handling  of 
milk  and  throughout  the  whole  cheese-making  process 
(pp.  8,  17). 

(1)  All  utensils,  especially  the  milk-strainer,   should  be 

thoroughly  washed  with  warm  water,  using  washing- 
powder,  and  then  scalded  with  live  steam. 

(2)  Milking  should  be  done  in  clean  places,  where  dust. 

cobwebs  and  flies  are  not  present. 

(3)  Milk  should  be  cooled  to  at  least  60°,  and  better  50° 

F.,  immediately  after  being  drawn  from  the  cow. 

(4)  Tainted  milk  should  not  be  received  at  the  factory 

from  any  patron.  If  uncertain  of  the  source  of 
tainted  milk  or  curd,  use  the  fermentation  test  on 
each  patron's  milk  (p.  434). 

(5)  A  small  amount  of  clean-flavored  starter  should  be 

used. 

(6)  Impure  or  bad-smelling  water  should  not.  be  used. 

(7)  There  should  be  screens  on  the  doors  and  windows  to 

prevent  the  entrance  of  flies. 

(8)  When  curd  is  washed,   only    pure  water    should  be 

used. 
Remedy  : 

(1)     Firm  the  curd  a  little  more  than  usual  in  the  whey  by 
raismg  the  temperature. 


Il8      SCIENCE   AND  PRACTICE   OF   CHEESE-MAKING 


(2)  Develop  a  little  more  acidity  before  removing  all  the 

whey. 

(3)  Mill  the  curd  early  and  expose  well  to  fresh  air  by 

stirring  for  some  time  immediately  after.  Excellent 
results  can  be  secured  at  this  time  because  each 
small  piece  of  curd  has  six  freshly  cut  surfaces  which 
permit  the  gases  and  odors  to  escape. 

(4)  Increase  the  amount  of  salt  in  curd  in  extremely  bad 

cases. 

(5)  Ripen  the  cheese  at  low  temperature. 

FRUITY  FLAVORS 


These  are  sweet  flavors,  having  an  odor  like  that  of 
certain  ripe  fruits,  such  as  pineapple,   raspberry  and 
strawberry.     Such  flavors  are  not  pleasant  to  the  taste 
and  are  rather  sickish. 
Cause : 

(1)  Bacteria  or  yeasts  carried  into  the  milk  by  dirt. 

(2)  Transporting  both  milk  and  whey  in  the  same  cans 

when  not  properly  cleansed. 

(3)  Exposing  milk  near  hog-pens  where  whey  is  fed. 
Prevention : 

(1)  Cans  used  for  delivering  milk  should  not  carry  whey, 

unless  they  are  emptied  and  thoroughly  cleansed 
immediately  after  being  brought  from  the  factory. 

(2)  All  whey  should  be  pasteurized  at  the  factories.     This 

would  not  only  reduce  greatly  the  source  of  badly 
flavored  milk,  but  it  would  eliminate  the  danger  of 
transmission  of  tuberculosis  through  the  whey. 

(3)  The    whey-tanks   should  be  cleaned  and  scalded  at 

least  twice  a  week.  A  steel  tank  has  the  following 
advantages:  It  is  more  durable  than  wood  or  ce- 
ment, does  not  leak,  does  not  absorb  whey,  is  easily 
cleaned,  and  is  cheaper  in  the  end. 

(4)  Use  a  clean-flavored  commercial  starter. 
Remedy : 

(1)  Firm  the  curd  a  little  more  in  the  whey  by  raising  the 

temperature. 

(2)  Develop  a  little  more  acidity  before  removing  whey. 

(3)  Air  the  curd  well  .after  milling. 

(4)  In  extreme  cases  use  more  salt  in  the  curd. 


DEFECTS    IN    FLAVOR  ,.          IK> 

BITTER  FLAVORS 

Indicated  by  a  bitter  taste  and  a  weedy  odor. 
Cause : 

(1)  Bacteria  and  yeasts. 

(2)  Allowing  cows  to  wade  in  and  drink  from  stagnant 

pools. 


Using  rusted  milk-cans  or  other  utensils. 

Using  old  starters  that  have  developed  toe  much  acid. 

Using  milk  delivered  in  cans  in  which  sour  whey  £rom 


dirty  tanks  is  carried. 
(6)     Too  little  salt  in  curd. 
Prevention : 

(1)  Milk  should  be  cooled  to  at  least  60°  P.,  and  better  to 

50°  P.,  immediately  after  milking. 

(2)  Rusted  cans  or  utensils  of  any  kind  should  not  carry 

milk. 


Cows  should  have  only  good  water. 
Clean-flavored  starters  only  should  be  used. 
Avoid  the  use  of  too  little  salt  in  the  curd. 


Remedy : 

(1)  Very  little  acidity  should  be  developed  before  remov- 

ing the  whey. 

(2)  Firm  the  curd  more  than  usual.     Heat  it  higher  in  the 

whey  and  stir  it  drier  when  removing  the  whey. 

(3)  Mill  early  and  expose  well  to  fresh  air  by  stirring. 

(4)  In  extreme  cases  use  more  salt  in  the  curd. 


FOOD  FLAVORS 

These  include  flavors  characteristic  of  the  foods 
eaten .  by  cows.  A  food  flavor  can  be  distinguished 
from  one  produced  by  bacteria  in  that  a  bacterial 
flavor  usually  gets  worse  as  the  cheese  ages,  while  a 
food  flavor  generally  passes  off  to  some  extent  (p.  8). 
Cause : 

(1)  Such  foods  as  turnips,  onions,  leeks,  weeds,  garlic, 
rape,  decayed  ensilage  and  certain  green  foddens 
(P-  ?)• 


12O       SCIENCE   AND   PRACTICE   OF   CHEESE-MAKING 

(2)  Exposing  milk  in  an  atmosphere  where  any  of  these 

are  exposed. 

(3)  Storing  milk  in  cellars  where  decayed  vegetables  are 

present . 

Prevention : 

(1)  Foods  that  impart  any  objectionable  flavor  to  milk 

should  not  be  fed  or  made  accessible  to  the  cow. 

(2)  Use  a  good  commercial  starter. 

(3)  Careful  and  thorough  aeration  (p.  12)  of  milk  is  often 

helpful  m  removing  odors  derived  from  foods 

Remedy : 

(1)  Heat  the   curd  several  degrees  higher  in  the  whey. 

The  high  temperature  helps  to  drive  off  the  volatile 
flavors. 

(2)  Air  the  curd  well,  especially  after  milling. 

(3)  Ripen  the  cheese  at  a  low  temperature. 


CHAPTER  XII 

Defects  in  Body  and  in  Texture 

Dry  Body 

Shown   in  cheese  that  is  too  firm,  mealy,  rubbery 
or  corky. 
Cause : 

Lack  of  moisture  or  milk -fat  or  both,  produced  by — 

(1)  Removing  part  of  the  fat  from  milk. 

(2)  Too  high  heating  in  the  whey. 

(3)  Heating  too  long. 

(4)  Too  much  stirring  at  the  time  of  removing  the  whey. 

(5)  Using  too  much  salt. 

(6)  Curing  cheese  in  an  atmosphere  that  is  too  dry  or  too 

hot. 

(7)  A  "high-cooked"  cheese  is  rubbery  or  corky;  one  that 

has  been  stirred  too  dry  is  mealy  or  sandy;  and  one 
that  is  dry  from  excess  of  salt  tastes  salty.  This  is 
a  convenient  way  of  determining  the  cause  of  such 
defects. 

Prevention : 

(1)  All  the  milk-fat  should  be  retained  in  the  cheese  as 

far  as  possible. 

(2)  The  lower  the  temperature    used  in  properly  firming 

the  curd,  the  better  will  be  the  texture  of  the  cheese. 

(3)  Be  absolutely  sure  of  the  correctness  of  the  thermome- 

ters used. 

(4)  Give  attention  to  the  moisture  content  of  the  curd; 

stir  the  curd  as  conditions  require;  and  use  the 
proper  amount  of  salt. 

Remedy : 

(1)  Pile  dry  curd  higher. 

(2)  Keep  the  air  moist  by  placing  hot  water  in  the  vat. 

(3)  Do  not  mill  the  dry  curd  early. 

(4)  A  dry  curd  can  be  made  mellow  by  soaking  in  cold 

water  after  milling,  but  the  cheese  will  not  have 
good-keeping  quality. 

(5)  Use  less  than  the  usual  amount  of  salt. 

121 


122       SCIENCE   AND   PRACTICE   OF    CHEESE-MAKING 


(6) 
(7) 


Paraffin  the  cheese  as  soon  as  practicable. 
Ripen  the  cheese  in  a  cool  room  where  the  humidity 
of  the  atmosphere  is  at  least  80  per  cent. 


ACID  BODY 


Cheese  under  this  head  may  be  either  dry  or  moist, 
but  in  either  case  is  of  a  mealy  or  sandy  character. 
It  has  a  sour  taste. 
Cause : 

(1)  Overripe  milk. 

(2)  Ripening  the  milk  too  much  before  adding  the  rennet. 

(3)  The    development    of   too   much   acidity   during   the 

cheese-making  process,  especially  before  the  whey 
is  removed. 

(4)  Acid  or  sour  cheese  is  most  frequently  caused  not  by 

developing  too  much  acidity,  but  by  having  the 
curd  insufficiently  firm  in  the  whey  when  the  acidity 
has  developed. 

(5)  Using  large  amounts  of  starter. 

Prevention : 

(1)  No  sour  milk,  or  milk  containing  more  than  0.26  per 

cent  of  acidity,  should  be  received  from  any  patron. 

(2)  The  rennet  should  be  added  when  the  milk  is  at  such 

a  stage  of  ripeness  that  there  will  be  time  to  firm 
the  curd  in  the  whey  before  too  much  acidity  has 
developed. 

(3)  Do  not  use  too  much  starter. 

(4)  Keep  the  development  of  acidity  under  control  by 

controlling  the  amount  of  whey  in  the  curd. 

Remedy : 

The  method  of  handling  overripe  or  spur  milk,  when  it  is 
absolutely  necessary  to  make  such  milk  into  cheese,  is  as  fol- 
lows: 

(1)  Heat  the  milk  not  above  84°  F. 

(2)  Use  an  extra  amount  of  rennet. 

(3)  Cut  the  curd  into  smaller  pieces. 

(4)  Heat  higher.     The  degree  of  heat  will  depend  on  the 

rapidity  with  which  the  acidity  is  developing. 
Most  fast-working  curd  contracts  rapidly  and  there- 
fore the  raising  of  the  temperature  can  be  hurried. 


DEFECTS  IN  BODY  AND  TEXTURE  123 

(5)  As  soon  as  possible  after  heating,  the  whey  should  be 
.   run  down  to  the  level  of  the  curd.     This  greatly 

facilitates  stirring  and  firming  the  curd,  and,  if  more 
than  one  vat  is  being  used,  time  is  saved  when  tjie 
remainder  of  the  whey  is  to  be  removed.  If  by  thi£- 
time  the  curd  is  not  firm  and  shows  too  much  acidity, 
a  sour  cheese  can  be  prevented  by, 

(6)  Removing  the  whey  and  putting  on  water  at  a  temper- 

ature of  102°  F.  The  amount  of  water  used  and  the 
time  it  is  left  on  will  depend  on  the  amount  of 
acidity  in  the  curd.  In  extreme  cases,  it  may  be 
necessary  to  give  a  second  treatment  with  water. 
As  soon  as  the  curd  becomes  firmed  in  the  water 
and  the  acidity  is  reduced  to  a  normal  amount,  the 
water  should  be  removed.  The  curd  should  then 
be  treated  like  a  normal  curd.  This  method  is  not  to 
be  confounded  with  the  "soaked-curd"  process, 
which  is  entirely  different. 

(7)  If,  after  milling,  the  curd  is  sour,  it  can  be  improved 

by  washing  in  pure  water  at  80°  F.  This  resembles 
the  "soaked-curd"  process,  and,  as  a  rule,  such 
cheese  does  not  keep  well.  However,  it  is  much 
better  to  do  this  than  to  allow  the  cheese  to  sour, 
and  the  process  should  be  used  in  extreme  cases, 

(8)  Use  an  extra  amount  of  salt  after  washing. 

LOOSE  OR  OPEN  TEXTURE 

Cheese   with   this   texture   is   full   of   holes.      Such 
cheese  is  generally  soft  in  body.     Such  defects  are 
more  serious   when  found  in  export  cheese,   since  a 
"close-boring"  cheese  is  demanded  for  this  trade. 
Cause : 

(1)  Developing  too  little   acid   and  retaining  too  much 

whey. 

(2)  Putting  curd  to  press  at  too  high  a. temperature. 

(3)  Lack  of  pressing. 

(4)  Soaking  curd  in  water  after  milling. 
Prevention : 

(1)  Have  at  least  0.24  per  cent    of  acidity  in  whey  run- 

ning from  curd  after  it  is  piled  for  cheddaring. 

(2)  The  curd  should  be  cooled  to  80°  F.,  at  least,  before 

pressing.  This  can  be  hastened  by  running  cold 
water  around  the  outside  of  the  vat  lining. 


124      SCIENCE   AND  PRACTICE  OF   CHEESE-MAKING 

(3)  Pressing  for  48  hours  is  much  better  than   for   24. 

A  continuous  pressure  is  of  more  value  than  a  heavy 
pressure  for  a  short  time. 

(4)  Curd  should  not  be  soaked  in  water. 

Remedy : 

(1)  Open-textured  cheese  can  be  closed  up  to  some  extent 

by  pressing  again. 

(2)  Ripen  at  lower  temperatures. 

GASSY  CHEESE  TEXTURE 

Indicated    by    the    presence    of    pin-holes.       Such 
cheese  usually  has  a  bad  flavor,  is  spongy,  and  the  curd 
may  float  on  the  whey  in  the  early  stage  of  cheese- 
making. 
Cause : 

(1)  Milk  infected  by  gas-producing  bacteria,  which  are 

carried  in  by  "dirt. 

(2)  Starters  infected  by  gas-producing  bacteria. 

Prevention : 

(1)  Gassy  milk  should  not  be  accepted  from  any  patron. 

(2)  Gassy  starters  should  not  be  used. 

Remedy : 

The  method  of  handling  gassy  milk  or  curd  is  as  follows: 

(1)  If  it  is  known  that  the  milk  is  gassy,  use  a  safe 

amount  of  clean  commercial  starter. 

(2)  Ripen  the  milk  a  trifle  more  before  adding  the  rennet. 

(3)  After  cutting,  stir  the  curd  till  the  whey  around  it 

shows  at  least  0.15  per  cent  of  acidity  before  heating. 

(4)  Heat  slowly.  Take  30  to  60  minutes. 

(5)  Care  should  be  taken  to  have  the  curd  not  too  firm 

in  the  whey  before  the  acid  begins  to  form.     The 
acidity  is  a  valuable  guide  at  this  time. 

(6)  A  little  more  acidity  should  be  allowed  to  develop 

before  removing  the  whey.     About  0.32  per  cent 
after  all  the  whey  is  off  is  sufficient. 

(7)  Should  the  curd  float,    remove  the  whey  to  such  an 

extent  that  it  can  not  float. 

(8)  Pile  gassv  curd  before  and  after  milling. 

(9)  After  milling,  the  curd  should  be  thoroughly  stirred 

and  aired  before  piling.     The  pressure  causes  the 
small  pieces  to  become  very  thin.     After  the  piling 


DEFECTS  IN   BODY  AND  TEXTURE  125 

and  airing  have  been  repeated  a  few  times  at  inter 
vals  of  15  to  20  minutes,  most  of  the  gases  should 
have  escaped.  The  pin-holes  will  then  have  be- 
come flattened  and  present  a  "dead"  appearance. 

(10)  The  whey  running  from  the  curd  at  this  time  should 

show  1.2  per  cent  of  acidity. 

(11)  Cool  the  curd  well  before  putting  in  press 

(12)  Press  for  48  hours  if  possible 

(13)  Ripen  in  a  cool  place 

GREASY  TEXTURE 

This  is  indicated  by  the  presence  of  free  fat  in  the 
mechanical  holes  in  the  cheese.     The  surface  of  the 
cheese    is    usually    greasy.      This    condition    is    most 
common  in  spring  and  in  times  of  drouth. 
Cause : 

fl)  Allowing  separation  and  hardening  or  drying  of  cream 
on  milk  before  manufacturing.  In  factories  that 
do  not  take  milk  on  Sunday,  the  trouble  is  always 
greatest  on  Monday. 

(2)  Abnormal  proportion  of  fat  to  casein  in  milk  in  times 

of  drouth  (p.  164). 

(3)  Heating   milk   too   high   or   too   long   before    adding 

rennet. 

(4)  Handling  curd  too  roughly. 

(5)  Piling  curd  too  much. 

(6)  Maturing  curd  at  high  temperature. 

(7)  Using  a  mill  that  bruises  the  curd. 

(8)  Ripening  cheese  at  high  temperatures. 
Prevention : 

(1)  Make  up  the  milk  daily,  or  take  pains  to  keep  the 

cream  stirred  in,  to  prevent  formation  of  dry  lumps 
that  cannot  be  worked  back  perfectly  into  the  milk. 

(2)  Cut  and  stir  the  curd  very  carefully  while  soft. 

(3)  Do  not  pile  the  curd  more  than  two  layers  deep. 

(4)  Do  not  heat  the  milk  or  curd  too  high.     Be  sure  of  the 

accuracy  of  the  thermometer  used. 

(5)  Use  a  mill  that  cuts  the  curd  without  squeezing  the 

fat  from  it.     The  knives  should  go  against  the  curd 
and  not  the  curd  against  the  knives. 

(6)  Apply  the  salt  soon  after  milling  and  mature  the  curd 

after  salting. 

(7)  Ripen  the  cheese  in  a  cool  room. 


I2O      SCIENCE  AND  PRACTICE   OF   CHEESE-MAKING 


Remedy  : 

(1)  Rinse  the  curd  with  water  at  90°  F.  before  salting. 

Then  use  a  trifle  more  salt. 

(2)  Cool  the  curd  before  putting  in  press. 

(3)  Use  large,  clean  press-cloths  to  insure  the  formation 

of  a  good  rind. 

(4)  Use  sufficient  hot  water  at  the  time  of  dressing  the 

cheese 


FISH-EYE  TEXTURE  OR  YEASTY  CHEESE 

This  is  indicated  by  holes  or  slits  resembling  the  eye 
of  a  fish.  (Fig.  30.)  This  is  usually  accompanied 
by  a  bitter  flavor.  The  first  indication  of  this  tex- 
ture is  the  formation  in  the  cheese  of  a  number  of 
small  pin-holes  surrounded  by  white  rings.  These 
gradually  enlarge  until  the  characteristic  slit-like 


FIG.     30 — TYPICAL     ILLUSTRATION    OF     THE     SLIT-LIKE     HOLES 
FORMED  IN  A  "YEASTY"  CHEESE 

openings  are  formed.  Usually  they  are  most  notice- 
able near  the  rind,  but  in  advanced  stages  extend 
throughout  the  whole  cheese.  If  present  in  colored 
cheese,  the  color  may  become  badly  mottled  as  the 
cheese  ages.  When  the  cause  of  this  trouble  is 
present  in  milk,  there  is  a  bitter  taste,  which  be- 
comes more  pronounced  as  the  acidity  of  the  milk 
increases. 


DEFECTS  IN  BODY  AND  TEXTURE  1 27 

Acidity  usually  appears  in  the  milk  quite  slowly,  even 
after  the  curd  has  been  first  cut.  When  the  formation 
of  acid  once  starts,  it  increases  very  rapidly.  This  is 
usually  during  the  interval  when  the  whey  is  removed. 
The  acid  increases  rapidly  and  the  curd  tends  to 
become  soft  or  mushy.  In  the  cheddaring  process  the 
curd  may  become  more  or  less  filled  with  large,  shining 
openings,  resembling  gas-holes.  After  milling,  the 
curd  is  usually  very  slow  to  contract  and,  in  severe 
cases,  may  soften  and  lose  its  body.  Frequently  yeasts 
are  accompanied  by  gas-producing  bacteria  and,  when 
this  combination  is  encountered  in  cheese-making,  it 
is  very  difficult  to  make  cheese  of  passable  quality. 
Whey  from  such  cheese,  when  whey  tanks  are  not 
frequently  cleaned,  may  appear  to  boil,  as  though  over 
a  fire. 

Cause : 

Yeasts  which  gain  entrance  to  milk.  They  have  been  found 
on  hay-dust,  leaves  of  trees,  in  unclean  cellars,  and  in  whey- 
tanks. 

(1)  In  cheese-factory  work,  the  whey  tank  is  the  great 

source  of  germ  contamination. 

(2)  Allowing  milk  to  be  exposed  to  the  dust  of  stables 

after  milking  (p.  6). 

(3)  Keeping  milk  too  warm  after  placing  it  in  the  cans. 

Prevention : 

(1)  After  milk  is  drawn,  it  should  immediately  be  taken 

into  a  clean  atmosphere  and  cooled  to  60°  F.,  and 
better  to    50°  F. 

(2)  Whey-tanks    should  be   cleaned   and   scalded    twice 

a  week,  at  least,  and,  better  still,  every  day. 

(3)  All  the  whey  should  be  pasteurized. 

(4)  All  cans  and  utensils  used  in  carrying  milk  should  be 

thoroughly  cleaned  and  scalded. 

Remedy : 

When  it  is  known  that  yeast -infected  milVt  has  been  re- 
ceived, it  should  be  treated  in  the  following  way: 


128      SCIENCE   AND   PRACTICE   OF    CHEESE-MAKING 


(1)  A  good  commercial  starter  should  be  used. 

(2)  The  rennet  should  be  added  when  the  milk  is  at  such 

a  stage  of  ripeness  that  there  will  be  time  to  firm 
the  curd  in  the  whey  before  too  much  acidity  has 
developed. 

(3)  Use    a    higher    temperature    for    heating.     Generally 

about  2°  F.  higher  is  sufficient. 

(4)  Remove  the  whey  with  as  little  acidity  as  is  necessary 

to  mature  the  curd  properly  in  cheddaring.  It  a 
good  starter  has  been  used,  an  acidity  of  0.24  per 
cent,  after  the  whey  is  all  removed  and  the  curd 
packed,  should  be  sufficient. 

(5)  Stir  the  curd  well  at  the  time  of  removing  the  whey. 

(6)  Do  not  pile  the  curd  high  in  cheddaring  unless  gas  'is 

present . 

(7)  Mill  the  curd  early  and  air  well  immediately  after. 

(8)  Should  the  curd  become  mushy  after  milling,  apply 

one-half  the  amount  of  salt  to  be  used.  Then  in 
about  an  hour,  or  as  soon  as  the  curd  has  shrunken 
and  the  holes  have  closed,  apply  the  balance  of  the 
salt. 

(9)  Curing  at  low  temperature  helps  to  check  the  slit 

formation  and  the  bitter  flavor. 


CHAPTER  XIII 

Defects  in  Color  and  in  Finish 

PALE  OR  ACID-CUT  COLOR 

This   term  refers   to   the  lighter  color  of  portions 
of  cheese  (p.  89). 

Cause : 

(1)  The  development  of  too  much  acid,  which  bleaches 

or  renders  paler  the  color  of  the  curd. 

(2)  Failure  to  firm  the  curd  in  the  whey  early  enough. 

(3)  Using  large  amounts  of  starter. 

(4)  Using  poor  cheese -coloring. 

Prevention : 

(1)  Have  the  curd  firmed  in  the  whey  before  the  acidity 
has  developed  to  more  than  0.18  per  cent. 

(2^  Cheese  should  be  colored  to  suit  the  market  for  which 
it  is  intended. 

Remedy : 

(1)  The  best  place  and  time  to  produce  a  bright,  even 

color  in  the  curd  is  in  the  whey,  while  the  whey  is 
being  removed.  From  the  time  the  whey  has 
reached  the  level  of  the  curd  till  it  is  all  removed, 
the  curd  should  be  well  stirred.  By  watching  the 
curd  during  this  handling,  the  color  can  be  seen  to 
develop  rapidly.  This  is  due  to  the  breaking  of  the 
film  of  moisture  which  surrounds  each  piece  of  curd. 

(2)  Allow  the  curd  to  stand  some  time  after  salting  before 

putting  in  press. 

MOTTLED  COLOR 

This   means   an   uneven   color,   most   noticeable   in 
colored  cheese. 

129 


I3O      SCIENCE   AND  PRACTICE   OF   CHEESE-MAKING 

Cause : 

(1)  An  uneven  development  of  acid  and  moisture  in  the 

curd. 

(2)  Uneven  cutting,  leading  to  an  uneven  contraction  of 

the  curd  when  heated  in  the  whey. 

(3)  Neglecting  to  strain  the  starter  when  lumpy. 

(4)  Adding  the  starter  after  adding  the  cheese-color. 

5)  Uneven  piling  and  maturing  of  the.  curd 

6)  Use  of  poor  cheese-color. 

7)  Mixing  the  curd  from  different  vats. 

8)  Lumpy  condition  or  the  curd  at  the  time  of  removing 

the  whey,  or  when  salt  is  applied. 
(9)  Adding   old  curd  to  fresh  curd  without  proper  pre- 
cautions. 

(10)  Yeasts.     When   due  to  these,  the  mottling  increases 
with  the  age  of  the  cheese. 

Prevention : 

v(l)  By  uniform 'cutting,  heating  and  stirring.  This  is 
facilitated;  by  the  use  of  a  5-1 6-inch,  perpendicular, 
wire  knife,  and  a  5 -8 -inch,  horizontal,  steel  knife. 

(2)  Each  small  piece  of  curd  should  be  kept  separated  from 

the  others  while  being  heated. 

(3)  The  starter  should  always  be  strained. 

(4)  The  starter  should  be  added  before  the   cheese-color 
.    A     is  added. 

(5)  The  curd  from  different  vats  should  not  be  mixed. 

(6)  In  using  old  curd,  it  should  be  placed  in  the  vat  about 

15  minutes  before  the  whey  is  removed. 

(7)  Curd  should  always  be  firmed  in  the  whey  before  too 

much  acid  has  developed. 

Remedy: 

When  the  curd  is  badly  mottled,  there  is  no  remedy  that 
will  make  the  color  uniform.     In  some  instances  the  color 
will  become  more  even  as  the    cheese    ages.     Preven- 
.  tion  is  the  bept,  remedy. 

SEAMY  COLOR 

This  is  a  condition  in  which  the  outline  of  each 
piece  of  curd  can  BeT  easily  seen  :  in  the  cheese. 
The  uniting  surfaces  are  marked  by  a  pale  line. 
(Fig- 3*) 


DEFECTS  IN   COLOR  AND  FINISH          .  l$J. 

Cause: 

(1)     Greasy  curds,  preventing  even  absorption  of  salt 
..  (2)     Impure  salt. 

Prevention : 

(1)  If  curds  are  very  greasy,  they  should  be  rinsed  off 

with  water  at  90°  F.  just  before  salting 

(2)  Only  high-grade  salt  should  be  used. 
Remedy : 

There  is  no  satisfactory  remedy.     Prevention  is  the  only 
sure  way  of  overcoming  the  trouble. 


FIG.     31 — ILLUSTRATION     OF    SEAMY   COLOR   AND  ALSO   OF  LACK 
OF  PRESSING 

RUSTY  SPOTS 

These   are   red   spots  resembling  rust,  and  usually 
located    in   the   little   pockets   of  fat  that   are   found 
where  two  pieces  of  curcl  come  together  in  pressing. 
This  is  most  noticeable  in  white  cheese. 
Cause : 

(f)      Bacillus  ruiensis, gaining  entrance  to  milk  or  curd. 
(2)     Unsanitary  buildings  and  surroundings.     When  whey 
leaks  through  the  factory  floor,  the  red  material 


13-2      SCIENCE  AND  PRACTICE  OF   CHEESE-MAKING 

formed  by  these  bacteria  may  develop.  The  in- 
fectious material  may  then  be  carried  into  the 
factory  by  wind  or  flies.  Once  in  the  factory,  every 
utensil  used  in  cheese-making  soon  becomes  infected 
and  the  trouble  constantly  increases. 

Prevention : 

(1)  Keep  everything  used  in  the  factory  absolutely  clean. 

(2)  Do  not  allow  the  factory  floor  to  leak.     Cement  floors 

are  the  most  sanitary. 

(3)  Keep  the  drain  and  drain-pipes  clean. 

(4)  Use  screen-doors  and  windows  during  fly  time. 
Remedy : 

(1)  The    only   way   to    get    rid   of   this   trouble  is  by  a 

thorough  cleaning  and  disinfection  of  the  factory 
surroundings  and  of  all  utensils. 

(2)  The  starter,  if  one  is  used,  should  be  renewed. 

METHOD    OF   CLEANING   AND    DISINFEC- 
TION 


(1)  Wash  all  utensils  with  a  brush,  hot  water,  and  wash- 

ing-powder, and  put  them  into  the  large  milk-vat. 

(2)  Put  a  cover  over  the  vat  and  turn  live  steam  into  it. 

(3)  Steam  the  utensils  for  at  least  one -half  hour. 

(4)  If  the  drains  are  dirty,  clean  them  with  hot  water 

and  washing-powder.  Then  steam  them  for  at  least 
20  minutes. 

(5)  If  the  ground,  surrounding  or  under  the  factory,  is 

infected,  have  it  covered  with  lime  or  fresh  earth. 

(6)  The  inside  walls,  cheese-shelves,  and  all  wood-work 

should  be  washed  with  a  hot  solution  of  bichlorid 
of  mercury  (corrosive  sublimate).  This  is  made  by 
dissolving  7|  grains  of  bichlorid  of  mercury  in  one 
pint  of  water.  Handle  this  substance  with  care  and 
apply  this  solution  with  a  brush  or  broom,  since  it 
is  a  powerful  poison. 

DEFECTS  IN  FINISH 

This  includes  anything  that  detracts  from  the  ap- 
pearance of  a  cheese.  As  a  rule,  such  defects  are 
due  to  carelessness  on  the  part  of  the  cheese-maker. 


DEFECTS   IX   COLOR  AND  FINISH  133 

UNCLEAN  SURFACES 
Cause : 

(1)  Placing  cheese  on  unclean  or  moldy  shelves  in  the 

curing-room. 

(2)  Using  dirty  hoops  or  handling  the  cheese  with  dirty 

hands. 

Prevention : 

(1)  Wash  the  shelves  after  each  shipment  of  cheese  leaves 

the  factory.  Use  a  brush,  hot  water,  and  some  good 
washing-powder  that  will  remove  grease.  Place  the 
shelves  in  the  sunlight  to  dry. 

(2)  Cheese-hoops  should  be  clean.     So  should  the  hands 

of  the  maker. 

CRACKED   RINDS 

These  are  openings  in  the  side  or  ends  of  the  cheese. 
They  are  unsightly  and  allow  cheese-flies  and  molds 
to  enter. 

Cause : 

(1)  Too  much  acid. 

(2)  Greasy  curd. 

(3)  Use  of  hard  press-cloths. 

(4)  Lack  of  pressing. 

(5)  Wrinkled  bandages. 

(6)  Too  dry  an  atmosphere  in  curing-room. 

Prevention : 

(1)  Avoid  excess  of  acid  in  making  cheese  (p.  S3). 

(2)  Rinse  greasy  curd  with  water  at  90°  F.  before  salting. 

(3)  Press-cloths  can  be  softened  by  soaking  in  a  weak 

solution  of  sulphuric  acid. 

(4)  Press  the  cheese  longer  before  dressing  and  have  the 

bandages  well  pulled  up. 

(5)  The  curing-room  atmosphere  should  show  80  per  cent 

humidity. 

Remedy : 

(1)  Press  the  cheese  again    after    washing    with    warm 

water.     If  this  fails, 

(2)  Paraffin  the  cheese. 


134      SCIENCE   AND  PRACTICE  OF   CHEESE-MAKING 

MOLDY  SURFACES 

This  condition  is  familiar.     The  formation  may  be 
of  several  colors. 

Cause : 

The  growth  of  molds  is  due  to 

(1)  Too  much  moisture  in  the  air. 

(2)  Too  high  temperature. 

(3)  Insufficient  circulation  of  air. 

(4)  Lack  of  cleanliness  m  curing-room. 

Prevention : 

(1)  Curing-rooms  should  be  so  equipped  that  the  temper- 

ature and  moisture  can  be  controlled. 

(2)  Good  circulation  of  air  should  be  provided. 

(3)  Curing-rooms  should  be  kept  clean. 

Remedy : 

(1)  By  spraying  cheese  with  formalin,  containing  10  per 

cent  of  formaldehyd. 

(2)  By  burning  sulphur,  3  pounds  to  1,000  cubic  feet  of  air. 

(3)  By  washing  the  ceilings,  walls,  shelves  and  all  wood- 

work with  a  hot  solution  of  bichlorid  of  mercury, 
made  by  dissolving  7J  grains  in  a  pint  of  water 
(p.  132). 

(4)  By  whitewashing  the  walls  and  ceilings 

UNEVEN  SIZES 

CROOKED  SIDES 

WRINKLED   BANDAGES 

COLLARS  ON  PRESS  ENDS 

All  these  are  common  defects  in  the  finish  of  cheese. 
They  are  found  in  almost  every  factory. 
Cause : 

Such  defects  are  nearly  always  due  to  carelessness  on:the 

...part  of  the  cheese-maker.     The  presses  may.be  worn 

'out  or  broken, 'the  followers  may  not  fit  the  hoops,  or 
too  heavy  pressure  may  be  applied  immediately  after 
dressing. 


DEFECTS  IN  COLOR  AND  FINISH  135 

Remedy : 

The  only  way  by  which  defects  m  finish  may  be  overcome 
is  by  proper  care  on  the  part  of  the  cheese-maker.  Very 
often  cheese  buyers  pay  less  money  for  cheese  of  a  good 
quality  when  it  is  poorly  finished.  If  the  cheese-maker 
has  to  pay  the  reclaim,  he  generally  becomes  more  care- 
ful. There  is  no  excuse  for  badly  finished  cheese,  be- 
cause it  is  within  the  power  of  every  cheese -maker  to 
make  cheese  with  good  finish.  A  poorly  finished  cheese 
is  a  disgrace  to  the  man  who  madfe  it. 


Part  III 

The 
Science  of  Cheese-Making: 

The  Chemical, 

Biological  and  Other  Relations 
of  Milk  and  Cheese 


Relations  of  the  Constituents  of  Milk  to 
Cheese. 

Relations  of  Micro-Organisms  and  En- 
zyms  to  Milk  and  Cheese. 

Changes  in  Cheese  During  tne  Ripening 
Process. 


187 


CHAPTER  XIV 

The  Constituents  of  Milk 

The  following  constituents  of  cow's  milk  are  of 
special  importance  in  cheese-making: 

(1)  Fat 

(2)  Casein 

(3)  Milk-sugar 

(4)  Salts 

(5)  Enzyms 

If  this  list  of  milk  constituents  is  compared  with 
a  complete  statement  of  the  composition  of  milk,  it 
is  noticeable  that  water  and  albumin  are  omitted. 
There  are  good  reasons  for  such  omission. 

So  far  as  the  process  of  cheese-making  and  the 
character  of  the  product  are  concerned,  the  amount 
of  water  in  normal  milks  requires  no  special  con- 
sideration. Slight  variations  in  conditions  of  the 
operations  of  cheese-making  affect  the  percentage 
of  water  in  cheese  much  more  than  the  variation  of 
the  percentage  of  water  in  normal  milks.  While 
dilution  of  milk  by  water  beyond  a  certain  propor- 
tion decreases  the  rapidity  and  completeness  of 
rennet  action  (p.  307),  the  amount  of  water. in  dif- 
ferent normal  milks  does  not  vary  enough  to  exert 
any  stich  retarding  influence  that  is  appreciable,  .so:  far 
as  our  observations  go. 

Milk-albumin  calls  for  little-  or  no  study  in  cheese- 
making,  since  it  remains  in  solution  during  the 

139 


140     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

cheese-making  process  and  passes  out,  for  the  most 
part,  with  the  whey.  Numerous  attempts  have  been 
made  to  recover  in  cheese  all  or  most  of  the  albumin 
present  in  milk,  but  we  know  of  no  case  which  has 
resulted  in  making  a  product  like  normal  cheddar 
cheese  in  its  properties. 

MILK-FAT 

Milk-fat,  also  known  as  butter-fat,  is  not  a  single 
chemical  compound,  but  is  a  somewhat  variable 
mixture  of  several  different  compounds  called 
glycerids.  Each  glycerid  is  formed  by  the  chemical 
union  of  glycerin  as  a  base  with  some  organic  acid 
or  acids  of  a  particular  kind  (butyric,  palmitic, 
oleic,  etc.).  Under  the  action  of  certain  kinds  of 
micro-organisms,  milk-fat  undergoes  decomposi- 
tion, forming  among  other  products  free  butyric  acid, 
which  is  the  compound  responsible  for  the  offensive 
flavor  of  rancid  cheese  and  butter. 

Fat-globules  in  milk. — Milk-fat  is  present  in  milk, 
not  in  solution,  but  suspended  in  the  form  of  very 
small,  transparent  globules.  The  globules  vary  in 
size,  the  smaller  being  more  numerous  than  the 
larger  ones.  The  average  size  of  fat-globules  in 
milk  is  somewhat  larger  than  one  ten-thousandth 
of  an  inch  in  diameter.  Contrary  to  what  has  been 
formerly  taught,  the  fat-globules  of  milk  have  no 
special  kind  of  covering,  but  are  simply  minute 
particles  of  fat,  floating  free  in  milk  in  the  form  of 
an  emulsion.  Skim-milk  and  whey  contain  few 
globules,  as  compared  with  normal  milk,  while 
cream,  of  course,  contains  many  more  than  normal 


CONSTITUENTS    OF    MILK  141 

milk.  Even  in  butter  and  cheese,  the  fat-globules 
of  the  milk  preserve  their  individuality  to  a  large 
extent. 

MILK-CASEIN 

Milk-casein  is  of  special  importance  in  connection 
with  cheese-making  because  the  conversion  of  milk 
into  cheese  is  dependent  upon  the  peculiar  proper- 
ties of  casein.  This  constituent  of  milk,  in  an  im- 
pure and  changed  form,  is  most  commonly  familiar 
as  the  solid,  white  substance,  called  curd,  which  forms 
in  milk  when  it  sours.  It  is  also  familiar  as  a  prom- 
inent constituent  of  separator-slime, .  and  in  this  form 
is  not  materially  changed  from  the  condition  in  which 
it  exists  in  milk. 

Composition  of  milk-casein. — Casein,  as  it  exists 
in  milk,  is  a  very  complex  chemical  compound,  be- 
longing to  a  general  class  of  nitrogen-containing  com- 
pounds known  as  protein,  and  to  a  special  subdivision 
called  phosphoproteins.  Its  elementary  composition  is 
about  as  follows. 

Carbon 53-OO  per  cent 

Oxygen    22.70  per  cent 

Nitrogen    I5-7O  Per  cent 

Hydrogen 7.00  per  cent 

Phosphorus    0.85  per  cent 

Sulphur   0.75  per  cent 

The  presence  of  phosphorus  in  casein  is  one  of 
its  distinguishing  chemical  features,  but  in  what 
particular  form  of  combination  the  phosphorus  ex- 
ists is  not  known  at  present.  Casein  in  milk  does 


142     SCIENCE    A,N;P    PRACTICE    OF   .CHEESE-  MA  KING 


s-an  uncprnbined  protein,  but  is,  accprd- 
the  /best  .evidence  available,  .in  combination 
with  some  form  of  calcium.  Three  general  views 
have  been  held  in  regard  to  the  relation  of  calcium 
(lime)  compounds  to  milk-casein:  (i)  That 
milk-casein  is  in  the  form  of  calcium  casein,  being 
combined  with  about  1.50  per  cent  of  calcium  oxid; 
(2)  that  casein  is  combined  directly  with  calcium 
phosphate;  (3)  that  the  compound  calcium  casein 
is  also  in  combination  with  calcium  phosphate. 
Some  .facts  appear  to  indicate  that  the  calcium 
casein  of  milk  is  a  form  containing  2.4  per  cent  of 
calcium  oxid.  It  has  been  well  established  that 
casein  forms  compounds  with  calcium,  but  which 
particular  form  of  combination  exists  in  milk,  as 
milk-casein,  we  cannot  yet  regard  as  settled  beyond 
question. 

Physical  condition  of  casein  in  milk.  —  For  a  long 
time  casein  was  believed  to  be  in  solution  in  milk 
and  is  still  held  to  be  so  by  those  who  have  ignored 
the  evidence  to  the  contrary.  Some  have  held  that 
it  was  in  a  state  of  semi-solution.  The  view  which 
must  now  be  regarded  as  representing  the  truth  be- 
yond all  doubt  is  that  casein  exists  in  milk  in  the 
form  of  extremely  minute,  gelatinous  particles  in 
suspension.  The  evidence  which  proves  the  Cor- 
rectness of  this  view  is  threefold:  (i)  While  the 
solid  particles  of  casein  are  so  small  that  they  easily 
pass  through  the  pores  of  fine  filter-paper,  they  do 
not  go  through  the  finer  pores  of  unglazed  porcelain 
(like  the  Chamberland  filter)  nor  through  animal 
membranes.  It  is.  thus  possible  to  strain  out  casein 
from  the  soluble  .portions  of  the  milk  in  quantities 


OF   MILK       i ,.    143 

sufficient  to  .see  and.exarnine^  X2)  Casein  is  sepa-i 
rated1; ; f  rom ;  milk :'. . by  eentri f  ugal  force,  being  dev; 
posited Jas;  .a  .film  on.  the  surrounding  walls  of  the; 
centrifuge.  :  By  whirling  milk  for  a  :  number;..: :dfe 
hours,  practically  all  -  of  the  casein  can  thus  be  sepa- 
rated from  the  milk.  It  is  thus  that  it  is  deposited 
on  the  walls  of  the  bowl  of  a  centrifugal  separator 
as  separator-slime,  in  which  the  casein,  in  a  gelat- 
inous form,  is  mixed  with  dirt  and  other  bodies: 
(3)  These  two  preceding  methods  of  proofs  should 
be  sufficiently  convincing  in  regard  to  the  insoluble 
condition  of  casein  in  milk;  but  the  latest  method 
removes  all  possibility  of  doubt.  Within  the  past 
few  months,  an  article  has  been  published  .by 
Kreidl  and  Neumann,  of  Vienna,  giving  results  of 
work  done  by  them  in  studying  milk  by  what  is  known 
as  "ultramicroscopic"  examination.  This  method  en- 
ables one  to  see  very  much  smaller  objects  than  can 
be  seen  by  the  usual  methods  of  microscopic  work. 
These' investigators  were  able  to  see  the  actual  par- 
ticles of  casein  swimming  in  milk,  to  treat 'them  with 
reagents  and  to  observe  their  various  transformations. 
Their  study  included  the  milk  not  only  of  cows,  but 
of  other  animals.  , 

Action  of  acids  upon  milk^casein.^Milk-casein  is 
madt  to  appear  in  milk  as:  a  heavyy  white  solid  or 
precipitate,  in  more -or  less  flocculent  form,  by  means 
of  dilute  acids,  even  by  carbon  dioxjd  under  certain 
conditions,  and  also  by  acid  salts.  .Treatment  by 
acids  changes  the  chemical  and  .  physical  properties 
of  milk-casein.  The  most  obvious  change  is  that 
of  physical  ,  condition,  the  very  minute/  invisible 


144     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

particles  of  casein  coming  together  into  large,  vis- 
ible aggregations.  The  cause  of  this  change  cannot 
yet  be  fully  explained.  It  has  been  usually  ex- 
plained by  saying  that  acids  unite  with  the  calcium 
of  the  calcium  casein,  and  the  casein,  thus  deprived 
of  its  combined  calcium,  is  changed  from  its  con- 
dition of  finely  divided,  gelatinous  particles  into 
larger  masses  and  then  appears  as  a  solid,  heavy 
precipitate.  This  explanation  is  not  entirely  satis- 
factory, since  casein  may  be  obtained  in  the  form  of 
a  precipitate  when  little  or  no  acid  is  present.  The 
effect  is  probably  to  be  ascribed  rather  to  the  forma- 
tion of  soluble  calcium  salts  by  the  acid  than  entirely 
to  the  direct  effect  of  acid  upon  the  calcium  of  milk- 
casein. 

When  milk  sours  in  the  ordinary  way,  the  lactic 
acid,  thus  formed,  acts  upon  the  calcium  casein, 
two  definite  changes  taking  place  when  sufficient  acid 
is  present.  First,  the  lactic  acid  combines  with  the 
calcium  of  the  calcium  casein,  forming  calcium 
lactate  and  calcium-free  casein  (casein  set  free  from 
its  combination  with  -calcium).  When  more  lactic 
acid  forms  than  is  sufficient  to  combine  with  the 
calcium,  the  second  change  takes  place ;  the  free 
casein  or  coagulum  takes  up  the  acid,  forming  a 
mixture  which  is  familiar  as  the  curd  of  sour  milk. 
It  was  formerly  believed  that  insoluble,  precipitated 
casein  combines  with  a  definite  quantity  of  acid, 
forming  a  definite  compound;  and  that,  under  this 
supposition,  the  curd  of  sour  milk  is  a  compound 
known  as  casein  lactate.  But  more  extended,  care- 
ful, and  accurate  work  has  shown  that  the  evidence 
was  misleading  upon  which  was  based  the  belief 


CONSTITUENTS    OF    MILK  145 

that  casein  unites  with  definite  quantities  of  acids 
to  form  definite,  insoluble  compounds.  Changes 
similar  to  those  occurring  when  milk  sours  in  the 
usual  way  take  place  when  milk  is  treated  with 
other  acids,  such  as  hydrochloric,  acetic,  sulphuric, 
etc. 

Free  casein  is  insoluble  in  water,  and  also  in  very 
dilute  acids  at  ordinary  temperatures.  The  action 
of  acids  on  calcium  casein  and  on  free  casein  is 
hastened  by  increase  of  temperature.  Less  acid  is 
required  at  higher  temperature  to  precipitate  casein. 
Casein  dissolves  easily  even  in  quite  dilute  acids, 
more  easily  at  higher  temperatures,  forming  soluble 
compounds  which  are  either  combinations  of  acid 
with  casein  or  decomposition  products  of  casein, 
according  to  the  concentration  of  the  acid,  the  tem- 
perature and  other  conditions  of  treatment. 

Action  of  alkalis  on  milk-casein. — Casein  is  acid 
in  character  in  that  it  unites  easily  with  fixed 
alkalis,  ammonia  and  alkaline  carbonates,  forming 
salts  easily  soluble  in  water.  Thus,  the  curd 
of  sour  milk  or  fresh  cheese  can  be  dissolved  by 
treatment  with  dilute  sodium  carbonate  or  am- 
monia. This  fact  is  made  use  of  in  cooking,  when 
tough,  insoluble  cheese,  such  as  that  often  made 
from  skim-milk,  is  rendered  more  easily  soluble  by 
use  of  baking-soda.  An  interesting  experiment  in 
this  connection  is  to  rub  in  a  mortar  some  pure 
casein,  suspended  in  water,  with  some  calcium  car- 
bonate. The  calcium  combines  with  the  casein,  and 
carbon  dioxid  gas  is  given  off.  The  soluble  com- 
pounds of  casein  with  alkalis  are  not  curdled  by 
rennet,  but  are  precipitated  on  treatment  with  acids. 


146     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

Some  of  these  salts  formed  by  casein  with  alkalis 
are  found  in  commerce  in  the  form  of  dietetic  and 
medicinal  preparations. 

Action  of  salts  on  milk-casein. — Milk-casein  may 
be  precipitated,  apparently  unchanged  chemically, 
by  saturating  milk  with  common  salt,  magnesium 
sulphate,  ammonium  sulphate,  etc.,  at  ordinary  tem- 
peratures. Milk-casein  is  also  precipitated  by  small 
amounts  of  solution  of  alum,  zinc  sulphate  and 
many  other  metallic  salts.  Calcium  chlorid  and 
some  other  salts  coagulate  casein  in  milk  heated  to 
9S0-«3°  F- 

Action  of  heat  on  milk-casein. — Heat  alone  under 
ordinary  conditions,  even  at  the  boiling  point  of 
water,  does  not  coagulate  the  casein  in  milk.  How- 
ever, heated  under  pressure  to  26$°-2&$0  F.,  casein 
salts  are  changed  in  their  properties  and  casein  itself 
is  coagulated.  The  browning  of  milk  heated  under 
pressure  is  more  or  less  due  to  changes  in  casein. 
The  formation  of  a  peculiar  skin  (haptogen  mem- 
brane) on  milk  heated  above  140°  F.  is  largely  due 
to  the  calcium  casein  of  the  milk  and  not,  as  was 
formerly  supposed,  to  albumin.  The  skin  itself 
contains  practically  all  of  the  constitutents  of  the 
milk  and  may  be  regarded  as  a  kind  of  evaporated 
milk.  On  removing  the  membrane,  a  new  layer  is 
formed  and,  by  removing  these  one  after  another, 
practically  all  of  the  milk  can  be  transformed  into 
the  membrane  condition.  It  appears  to  be  due  to 
surface  evaporation. 

Action  of  rennet  on  milk-casein. — One  of  the 
most  characteristic  properties  of  milk-casein  is  its 
coagulation  by  the  enzym  or  chemical  ferment  con- 


CONSTITUENTS    OF    MILK  147 

tained  in  rennet.  This  property  makes  possible 
the  manufacture  of  cheddar  and  many  other  kinds 
of  cheese  from  milk.  The  curd  formed  by  the  action 
of  rennet  is  called  paracasein  or,  more  properly,  cal- 
cium paracasein.  The  coagulation  of  milk-casein  pro- 
duced by  rennet  is  quite  different  from  that  produced 
by  acids.  Calcium  paracasein  behaves,  in  general, 
much  like  casein  toward  acids  and  alkalis.  The  details 
of  rennet  action  on  milk-casein  will  be  considered  more 
fully  in  Chapter  XXII  (p.  299). 

Other  changes  caused  in  milk-casein. — Under  the 
action  of  chemical  reagents,  of  enzyms  and  of  various 
micro-organisms,  calcium  casein  and  paracasein 
may  be  changed  into  a  large  number  of  other  sub- 
stances. Among  the  compounds  and  classes  of  com- 
pounds thus  formed  are  caseoses  (albumoses), 
peptones,  amino  acids  (crystallizable  bodies)  and 
ammonia.  These  products  are  never  found  in  nor- 
mal milk  as  it  leaves  the  cow's  udder,  but  may  be 
present  in  milk  that  has  stood  exposed  to  air  for  some 
time. 

Brine-soluble  substance  formed  from  casein. — 
When  milk  is  treated  with  rennet  and  the  curd 
is  handled  in  the  usual  manner  followed  in  cheese- 
making,  a  most  interesting  change  begins  to  take 
place,  which  becomes  especially  prominent  in  the 
cheddaring  operation  (p.  32).  The  curd  changes 
into  a  form  which  is  soluble  in  a  warm  solution  of  5 
per  cent  brine  (common  salt) ;  at  the  same  time,  the 
curd  forms  long  strings  on  a  hot  iron  and  acquires  the 
peculiar  texture  of  the  cooked  meat  of  a  chicken's 
breast,  with  a  characteristic  velvety  mellowness  of  feel- 
ing and  glistening,  silky  appearance.  These  changes 


148     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


are  due,  apparently,  to  the  formation  of  ^this  brine- 
soluble  substance.  More  or  less  of  this  peculiar 
substance  remains  in  the  cheese  indefinitely.  For 
example,  in  a  cheese  two-and-one-half  years  old, 
the  portion  of  the  cheese  insoluble  in  ether  (fat) 
and  in  warm  water  consisted  entirely  of  this  brine- 
soluble  substance.  On  being  warmed,  it  could  be 
drawn  out  in  strings  over  a  yard  long.  (Figs.  32 
and  33.) 


FIG.      32  —  BRINE-S  0  L  U  B  L  E       FIG.     33 — STRINGS     OF    BRINE- 


CHEESE     PROTEIN      WARMED 
AND        FRESHLY        DRAWN 
OUT    IN  A    STRING    SEV- 
ERAL    FEET     LONG 


SOLUBLE  PROTEIN  OF 

CHEESE    SUSPENDED    AND 

DRIED.    STRINGS    ABOUT 

FOUR       FEET       LONG 


MILK-SUGAR 

Milk-sugar,  also  called  lactose,  is  present  in  cow's 
milk  in  solution.  In  general  composition,  it  re- 
sembles ordinary  sugar,  but  it  is  less  sweet  and 
less  soluble  in  water ;  however,  it  differs  much  from 


CONSTITUENTS    OF    MILK  149 

ordinary  sugar  in  its  chemical  behavior  and  espe- 
cially in  its  relations  to  various  ferments.  The 
amount  of  sugar  in  milk  varies  from  below  4  to 
over  6  per  cent  and  averages  about  5  per  cent. 
Variation  in  the  amount  of  sugar  in  different  nor- 
mal milks  has  little  interest  in  connection  with  the 
operations  of  cheese-making  for  the  reason  that 
there  is  always  an  abundance  for  cheese-making 
purposes.  The  milk-sugar  passes  largely  into  the 
whey  in  the  cheese-making  process  and  forms  a 
large  percentage  of  the  solids  in  whey.  The  milk- 
sugar  of  commerce  is  usually  prepared  by  evaporat- 
ing whey  and  purifying  the  impure  product  first 
obtained.  The  importance  of  milk-sugar  in  cheese- 
making  depends  on  the  fact  that  it  is  easily  con- 
verted into  lactic  acid  by  certain  forms  of  bacteria. 
In  the  making  of  cheddar  cheese,  only  a  small  pro- 
portion of  the  sugar  is  changed  into  lactic  acid  during 
a  considerable  part  of  the  process,  but  one  per.  cent  or 
more  is  so  changed  by  the  time  the  curd  is  salted.  In 
cheese  made  from  sour  milk,  such  as  cottage  cheese, 
and  in  starters  used  in  cheese-making,  somewhat 
more  than  one-fourth  of  the  milk-sugar  is  changed 
and  there  is  formed  in  such  cases  about  0.7  or  0.8 
per  cent  of  lactic  acid.  When  milk  or  whey  is 
allowed  to  stand  for  some  time  at  ordinary  tem- 
peratures, over  i  per  cent  of  lactic  acid  may 
be  formed.  Hence,  sour  milk  or  whey,  when  two 
or  three  days  old,  usually  contains  only  3.5  to  4 
per  cent  of  milk-sugar.  In  cheddar  cheese  made 
under  normal  conditions,  we  never  find  any  un- 
combined  or  free  lactic  acid,  since  it  combines  with 
calcium  of  certain  calcium  salts  in  the  milk  to  form 


I5O     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

calcium  lactate,  a  compound  which  is  neutral 
(neither  acid  nor  alkaline),  and  which  does  not 
taste  sour.  Under  the  usual  forms  of  fermentation, 
milk-sugar  forms  small  amounts  of  other  com- 
pounds in  addition  to  lactic  acid.  The  sour  smell 
of  whey  and  of  sour  milk  is  not  due  to  free  lactic 
acid,  since  pure  lactic  acid  has  practically  no  odor, 
but  is  caused  by  some  of  the  other  fermentation 
products  formed,  the  exact  nature  of  which  is  not 
fully  known. 

THE  SALTS  OF  MILK 

The  salts  of  milk,  commonly  represented  by  the 
term  "ash,"  are  present  in  only  small  amounts,  but 
they  have  extremely  important  relations  to  the 
process  of  cheese-making.  Our  knowledge  of  these 
compounds  is  very  incomplete.  The  salts  of  milk 
are  commonly  spoken  of  as  the  ash  or  mineral  con- 
stituents. This  conception  is  somewhat  misleading, 
because  the  materials  appearing  in  the  ash  of  milk 
are,  to  some  considerable  extent,  .combined  in  or- 
ganic compounds,  instead  of  existing  in  milk  as 
separate  inorganic  bodies  in  the  form  in  which  they 
appear  in  the  ash.  The  ash,  therefore,  represents 
in  amount  more  than  the  so-called  mineral  con- 
stituents of  milk  and  less  than  the  salts  of  milk. 
While  the  average  amount  of  ash  in  milk  is  about 
0.7  per  cent,  the  amount  of  salts  is  probably  much 
nearer  0.9  per  cent.  To  illustrate  this  point  in  more 
detail,  the  citric  acid  which  is  present  in  milk  in 
the  form  of  citrate  salts  does  not  appear  at  all 
in  the  ash,  since  it  is  destroyed  in  burning  the  milk 
to  obtain  the  ash.  In  cheddar  cheese  the  ash,  not 


CONSTITUENTS    OF    MILK  15! 

including  the  salt  added  in  cheese-making,  rep- 
resents the  salts  of  the  milk  even  less  accurately 
than  in  milk.  In  cheese,  we  have  a  considerable 
amount  of  calcium  lactate,  but,  in  obtaining  the  ash 
of  cheese,  the  lactic  acid  portion  is  destroyed  and  so 
does  not  form  a  part  of  the  ash.  The  percentage 
of  ash  in  green  cheese  due  to  constituents  obtained 
from  the  milk  is  usually  between  2  and  3  per  cent, 
varying,  of  course,  with  the  amount  of  whey  retained 
in  the  cheese. 

In  milk,  a  portion  of  the  salts  is  present  in 
soluble,  and  a  portion  in  insoluble,  form.  The  fol- 
lowing portions  of  the  salts  of  milk  are  present  in 
solution :  Sodium,  potassium,  chlorine,  and  citric 
acid  compounds;  amounts  of  phosphoric  acid  in 
the  form  of  combined  phosphates  varying  in  differ- 
ent milks  from  45  to  65  per  cent  of  the  total  phos- 
phoric acid  present;  25  to  45  per  cent  of  the  calcium 
(lime)  ;  and  over  50  per  cent  of  the  magnesium. 
In  what  specific  forms  of  compounds  these  ele- 
ments are  present  in  milk  is  not  known  and  the 
problem  is  a  difficult  one  to  solve.  The  sugges- 
tion has  been  made  by  Soldner  that  something  like 
the  following  arrangement  may  be  supposed  to 
exist : 

Percentage  of  the  total 
Compounds  salts  in  milk 

Calcium  citrate 23.6 

Mono-potassium  phosphate 12.8 

Sodium  chlorid 10.6 

Potassium  chlorid 9.2 

Di-potassium  phosphate 9.2 

Tn-calcium  phosphate 8.9 

Di-calcium  phosphate 7 .4 

Potassium  citrate 5.5 

Calcium  oxid  in  casein 5.1 

Magnesium  citrate 4.0 

Di-magnesium  phosphate 3.7 


152     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

Whether  this  suggested  distribution  of  com- 
pounds among  the  salts  of  milk  is  near  the  truth 
or  not,  it  emphasizes  the  fact  that  the  matter  is 
one  of  no  little  complication.  Some  investigators 
believe  that  the  calcium  phosphate  exists  entirely  as 
tri-calcium  phosphate ;  others,  as  the  di-calcium  com- 
pound, probably  on  the  basis  of  better  evidence.  The 
presence  of  soluble  acid  phosphate  and,  probably,  of 
acid  citrate  also,  accounts  for  a  part  of  the  acidity  of 
fresh  milk. 

When  milk  is  heated,  the  amount  of  soluble  calcium 
salts  is  decreased  as  the  result  of  being  changed  to 
insoluble  forms. 

The  presence  of  soluble  calcium  salts  in  milk  is 
essential  to  the  coagulation  of  milk  by  rennet-extract 
(p.  306). 

Acidity  of  milk. — In  this  connection,  we  will  call 
attention  to  the  acidity  of  fresh,  normal  milk.  Milk 
in  which  lactic  acid  has  had  no  chance  to  develop  has 
the  power  of  neutralizing  alkalis  and  in  that  respect 
behaves  like  a  solution  containing  acid. 

The  acidity  of  fresh  milk  varies  with  a  number  of 
conditions,  such  as  (i)  the  milk  of  the  same  ani- 
mal at  different  times,  (2)  the  milk  of  different 
cows,  and  (3)  with  the  stage  of  lactation,  being 
highest  at  the  beginning  of  lactation  and  gradually 
decreasing  with  the  advance  of  the  lactation  period. 
The  acidity  of  fresh  normal  milk  is  caused  by  no 
one  substance,  but  is  due  to  the  presence  of  (i) 
acid  phosphates,  (2)  citrates  and  (3)  casein.  It 
has  been  found  to  vary  widely,  from  below  4  to  over 
10,  expressed  as  cubic  centimeters  of  one-tenth 
normal  alkali,  but  in  most  cases  it  is  between  7 
and  9. 


CONSTITUENTS    OF    MILK  153 

Lactic  acid  begins  to  be  formed  in  milk  soon 
after  it  is  drawn,  if  the  milk  is  not  kept  below  50° 
F.  By  the  time  milk  reaches  the  factory,  the  nor- 
mal acidity  of  the  milk  is  usually  increased  about 
0.05  to  o.io  per  cent,  corresponding  to  a  total 
acidity  of  0.12  to  0.18  per  cent.  In  warm  weather, 
the  acidity  often  exceeds  0.20  per  cent  in  the  case  of 
some  herds.  The  increase  of  acidity  over  that  ex- 
isting in  fresh  normal  milk  is  an  indication  of  the 
temperature  at  which  the  milk  is  kept  and  also  of 
the  cleanliness  observed  in  milking  and  in  caring  for 
the  milk  and  the  dairy  utensils  with  which  the  milk 
comes  in  contact  (see  p.  4).  An  acidity  equivalent 
to  0.20  per  cent  of  lactic  acid  in  milk  when  received 
at  the  factory  is  regarded  as  the  danger  line  for  ched- 
dar  cheese-making.  Generally,  only  a  part  of  the 
milk  taken  to  a  cheese-factory  will  exceed  this  limit, 
so  that  the  average  for  the  day  may  be  considerably 
below  the  0.20  per  cent  limit. 

MILK-ENZYMS 

Enzyms  are  chemical  ferments;  they  have  the 
power  to  produce  changes  in  other  substances  with- 
out themselves  undergoing  change.  Enzyms  are 
the  products  of  living  cells.  According  to  recent 
views,  normal  milk  is  not  to  be  regarded  as  an  in- 
active fluid,  but  possesses  certain  properties  char- 
acteristic of  living  substances.  Normal  milk  gives 
evidence  of  the  presence  of  several  different  en- 
zyms,  among  which  are  those  called  (i)  diastase, 
(2)  galactase,  (3)  lipase,  (4)  catalase,  (5)  peroxi- 
dase  and  (6)  reductase.  The  subject  has  not  been 
sufficiently  studied  to  enable  one  to  make  anything 


154     -SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

like  a  clear  or  satisfactory  presentation.  It  is  quite 
probable  that  some  of  these  enzyms,  now  described 
under  different  names,  are  the  same  or  are  mix- 
tures. The  quantity  of  these  substances  is  so  ex- 
tremely small  and  the  methods  of  separating  them 
in  pure  form  are  so  imperfect  that  their  study  pre- 
sents peculiar  difficulties.  One  of  the  main  prac- 
tical uses  to  which  enzyms  in  milk  have  been  put 
depends  upon  the  fact  that  their  presence  serves  to 
distinguish  unheated  from  boiled  milk,  because  the 
enzyms  are  all  destroyed  by  heat.  We  shall  not 
consider  these  substances  in  detail  because,  so  far 
as  we  now  know,  most  of  them  are  not  concerned 
in  cheese-making.  Galactase  is  the  only  one  of  special 
interest  in  this  connection.  This  was  discovered  at 
the  Wisconsin  experiment  station  in  1897  and  has 
received  considerable  attention  in  connection  with 
studies  of  milk  and  cheese.  We  shall  consider  this 
enzym  in  more  detail  later  (p.  297). 


CHAPTER  XV 

Conditions  Affecting  Proportions  of 
Constituents  in  Milk 

In  studying  the  composition  of  milk  from  dif- 
ferent cows  or  herds,  one  of  the  first  facts  noticed 
is  that  the  same  constituents  vary  in  amount  more 
or  less  widely  in  different  milks.  This  fact  is  of 
the  highest  importance  in  studying  the  relations 
of  milk  to  cheese-making.  As  a  foundation  for 
a  more  detailed  consideration  of  these  relations  of 
milk,  it  seems  desirable  that  we  should  study  with 
some  degree  of  fullness  the  more  important  condi- 
tions which  cause  variation  in  the  amounts  of 
constituents  of  milk.  Those  constituents  of  great- 
est interest  to  us  which  vary  most  are  fat  and 
casein.  Milk-sugar  and  salts  vary  only  slightly 
as  compared  with  the  amount  of  variation  in  fat 
and  casein.  We  shall  find  it  to  be  a  matter,  not 
only  of  interest,  but  of  practical  importance,  to  study 
the  extent  of  these  variations  and  their  causes, 
and  also  to  learn  to  what  extent  different  influences 
affect  the  relation  of  fat  to  casein.  As  we  shall 
show  later  (p.  186),  the  percentages  of  fat  and 
casein  in  milk  largely  determine  the  yield  of  cheese; 
while  the  proportion  of  these  two  constituents,  relative 
to  each  other,  determine  the  composition  (p.  231) 
and  to  a  considerable  degree,  the  quality  of  cheese 
(P-  243)- 


156     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

AMOUNT  OF  FAT  IN  MILK 

The  percentage  of  fat  in  normal  milk  varies 
greatly,  much  more  than  any  other  constituent, 
especially  if  we  consider  single  milkings  of  individ- 
ual cows.  In  connection  with  the  manufacture  of 
cheese,  we  are  more  particularly  interested  in 
knowing  the  percentage  of  fat  in  the  milk  of  dif- 
ferent herds  of  cows  rather  than  in  that  of  single  indi- 
viduals. In  the  case  of  single  herds  of  cows,  such 
as  are  common  in  the  dairy  region  of  New  York 
state,  the  lowest  percentage  of  fat  found  on  any 
one  day,  as  the  result  of  special  investigations, 
was  2.90;  the  highest,  5.50,  which  occurred  late  in 
the  season  (October).  Taking  the  average  of  dif- 
ferent herds  of  cows  for  an  entire  cheese-factory 
season  (April  to  November),  the  lowest  percentage 
of  fat  was  3.31  and  the  highest,  4.31.  In  the  case 
of  cheese-factory  milk,  consisting  of  a  mixture  of 
the  milk  of  different  herds,  the  lowest  percentage 
of  fat  found  was  3.04  and  the  highest,  4.60.  The 
average  percentage  of  fat  in  mixed  factory  milk 
for  an  entire  season  is  about  3.75 ;  and  this  average 
has  been  found  to  vary  only  slightly  in  different 
factories  and  in  different  seasons.  The  Wisconsin 
experiment  station  reports  3.64  as  the  season's 
average  percentage  of  fat  in  the  milk  of  347  fac- 
tories. In  the  case  of  individual  factories,  a  sea- 
son's average  as  low  as  3.20  per  cent  is  given.  The 
lowest  percentage  of  fat  in  the  milk  of  any  single 
herd  for  a  single  day's  milk  is  given  as  2.30,  while 
the  highest  reported  is  5.  Results  reported  in  Can- 
ada appear  to  indicate  a  lower  percentage  of  fat  in 
milk  than  in  the  case  of  New  York. 


VARIATIONS    OF    MILK    CONSTITUENTS  157 

While  many  conditions  cause  the  percentage  of  fat 
in  milk  to  vary,  we  will  notice  only  three  as  of  special 
importance  in  connection  with  cheese-making:  (i) 
Breed,  (2)  stage  of  lactation,  and  (3)  change  from 
barn  to  pasture. 

Influence  of  breed  of  cows  on  fat  content  of  milk. 
— The  influence  of  what  is  known  as  breed  upon 
the  composition  of  cow's  milk  has  been  long  recog- 
nized and  extensively  studied  in  a  general  way, 
but  only  in  a  comparatively  limited  way  in  its  rela- 
tion to  cheese-making.  It  is  largely  owing  to  this 
influence  that  we  find  the  milk  of  one  country  dif- 
fering from  that  of  another,  or  the  milk  of  one 
section  of  a  country  differing  from  that  of  another 
section.  For  example,  the  average  percentage  of 
fat  in  milk  in  Germany  and  Holland  is  fully  one- 
half  per  cent  lower  than  in  New  York  state,  and 
probably  in  the  United  States  at  large,  because  the 
prevailing  breeds  of  cows  there  are  those  producing 
milk  comparatively  low  in  fat.  The  results  of 
recent  tests  go  to  show  that  in  Canada  the  milk 
in  Quebec  province  contains  more  fat  than  does 
that  of  Ontario,  since  in  the  former  the  native 
Jerseys  are  the  predominant  breed,  while  in  the 
latter,  Holstein-Friesians,  Ayrshires  and  Short- 

PERCENTAGE  OF  FAT   IN    MILK  OF  DIFFERENT  BREEDS  OF 

COWS 

Name  of  breed  Per  cent  of  fat  in  milk 

Holstein-Friesian 3.26 

Ayrshire 3.76 

American  Holderness 4.01 

Shorthorn 4.28 

Devon 4,89 

Guernsey S.38 

Jersey 5.78 


158     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

horns  prevail.  The  foregoing  table  represents  aver- 
ages in  the  case  of  three  to  six  individuals  of  each 
of  seven  different  breeds  for  an  aggregate  of  four 
to  twenty  lactation  periods  with  each. 

Influence  of  stage  of  lactation  on  fat  content  of 
milk. — From  the  time  a  cow  "comes  fresh  in  milk" 
up  to  the  time  she  becomes  "dry,"  the  composition 
of  the  milk  undergoes  gradual  changes,  which  are 
quite  independent  of  other  factors.  The  period  of 
lactation  varies  in  length  with  different  individual 
cows,  but,  for  practical  purposes,  lasts  about  10  to 
12  months.  The  changes  observed  in  the  percent- 
age of  fat  during  the  progress  of  the  lactation 
period  are  quite  marked  and  fairly  regular,  with- 
out reference  to  individual  or  breed.  The  colos- 
trum, which  is  the  secretion  produced  by  a  cow 
soon  after  calving,  is  very  different  in  composition 
from  normal  milk  and  is  not  considered  at  all  in 
our  discussion  of  the  constituents  of  milk,  because 
it  has  no  interest  for  us  in  this  connection.  The 


VARIATION     OF     PERCENTAGE     OF     FAT     IN     MILK     WITH 
ADVANCE  OF  LACTATION 


Month  of  lactation 

Per  cent  of 
fat  in  milk 

Percentages  in 
comparison  with 
first  month 

1.. 

4  30 

I::-:  

4.11 
421 

95.6 

4. 

4  ?"> 

S  

4  38 

?:;;;;;.•;  

8. 

4.53 
4.57 

4  ^0 

105.3 
106.3 

9 

106.8 

10  

4  90 

108.6 

11  :.:::::: 

5.07 

118.0 

VARIATIONS    OF    MILK    CONSTITUENTS 


159 


figures  presented  in  the  table  on  page  158  represent 
the  monthly  averages  of  nearly  100  different  lactation 
periods. 

In  studying  this  table,  we  notice  that  the  per- 
centage of  fat  decreases  in  the  second  month,  as 
compared  with  the  first,  and  then  begins  to  in- 
crease, continuing  to  increase  from  month  to  month 
during  the  entire  period  of  lactation.  The  rate  of 
increase  is  more  rapid  during  the  last  two  or  three 
months  than  previously.  Such  behavior  appears 
to  be  the  general  rule.  Variation  from  the  com- 
parative degree  of  regularity  observed  in  the  fore- 
going table  may,  of  course,  appear  in  the  case  of 
individuals. 

It  will  be  a  matter  of  more  immediate  interest  to 
consider  the  influence  of  advancing  lactation  upon  the 
percentage  of  fat  as  observed  in  the  case  of  milk 
used  at  cheese-factories.  In  general,  dairymen 
have  their  cows  begin  the  period  of  lactation  in 
March  and  April,  so  that  milk  taken  to  a  cheese- 
factory  represents,  during  the  season,  stages  of  the 
lactation  period  extending  from  about  the  second 


VARIATION     OF     FAT     IN     CHEESE-FACTORY     MILK     WITH 
ADVANCE  OF   LACTATION 


Month 

Per  cent  of  fat 
in  milk 

Percentages  in  com- 
parison with  first  nionth 

April... 
May  

June  .  . 

New  York 
3.43 
3.58 
3.64 
3.62 
3.84 
3.98 
4.23 

Wisconsin 
3.48 
3.49 
3.50 
3.55 
3.63 
3.84 
4.08 

New  York 
100.0 
104.4 
106.1 
105.5 
112.0 
116.0 
123.3 

Wisconsin 
100.0 
100.3 
100.6 
102.0 
104.3 
110.3 
117.2 

July  
August. 

September  

October  

160     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

to  the  eighth  months.  Cows  kept  under  ordinary 
farm  conditions  are  subject  to  greater  variations 
of  external  influences  than  those  used  in  the  investi- 
gation represented  by  the  figures  in  the  preceding 
table.  The  figures  in  the  table  on  page  159  repre- 
sent results  secured  in  New  York  and  Wisconsin. 

Influence  of  change  from  barn  to  pasture  upon 
the  percentage  of  fat  in  milk. — In  the  course  of  a 
study  of  cheese-factory  milk  in  New  York,  it  was 
noticed  that,  under  certain  conditions,  a  marked 
change  in  percentage  of  fat  in  milk  took  place. 
Each  year  while  the  study  of  factory  milk  was  carried 
on,  it  was  observed  that  about  the  middle  of  May 
there  was  a  considerable  increase  in  the  percentage 
of  milk-fat,  accompanied  by  an  increase  of  other 
solids  and  also  by  a  larger  yield  of  milk.  Thus, 
during  the  first  half  of  May,  the  milk  contained 
3.46  per  cent  of  fat  and,  during  the  second  half, 
3.70  per  cent.  These  results  are  in  agreement  with 
those  reported  by  the  Vermont  and  Wisconsin  ex- 
periment stations  and  also  by  the  Ontario  agricul- 
tural college.  This  question  has  been  more  thor- 
oughly studied  at  the  Vermont  experiment  station 
than  elsewhere  and,  according  to  the  results  ob- 
tained during  a  series  of  years,  the  general  rule 
shows  a  change  like  that  noticed  above,  but  in  some 
years  little  or  no  change  could  be  observed.  A 
careful  study  of  all  the  available  facts  appears  to 
justify  the  explanation  that  the  increased  per- 
centage of  fat  in  milk  under  the  given  circum- 
stances was  due  to  a  marked  change  in  the  char- 
acter of  the  food  and  environment  of  the  cows, 
since  they  were  turned  out  to  pasture  about  the 


VARIATIONS    OF    MILK    CONSTITUENTS  l6j 

middle  of  May.  Under  the  known  existing  condi- 
tions of  the  food  and  environment  of  cheese-factory 
cows,  there  was  thus  a  change  from  dry  food  of 
an  indifferent  character,  mainly  straw  or  poor  hay 
without  grain,  to  a  highly  succulent  food  of  a  most 
palatable  kind.  It  is  probable  also  that  the  changes 
in  the  environment  of  the  cows  from  confinement 
in  barn  and  yard  to  the  freedom  of  pasture  exercised 
a  beneficial,  physiological  influence. 

AMOUNT  OF  CASEIN  IN  MILK 

The  percentage  of  casein  in  normal  milk  varies 
quite  widely,  though  much  less  than  in  case  of 
milk-fat.  In  the  single  milkings  of  individual  cows, 
we  have  found  casein  as  low  as  1.59  per  cent  and 
as  high  as  4.49  per  cent.  The  highest  percentages 
were  found  in  the  case  of  cows  far  along  in  lacta- 
tion and  giving  only  small  amounts  of  milk.  In 
the  case  of  individual  herds  of  cows,  the  percentage 
of  casein  ranged  from  1.79  to  3.02.  In  the  case  of 
milk  consisting  of  a  mixture  of  the  milk  of  several 
different  herds,  the  percentage  of  casein  varied  from 
1.93  to  3.00. 

The  conditions  which  influence  variation  of  casein 
in  milk,  so  far  as  they  are  of  special  interest  to  us 
here,  are  (i)  breed,  (2)  stage  of  lactation,  (3) 
change  from  stable  to  pasture,  and  (4)  effects  of 
drouth. 

Influence  of  breed  of  cows  on  percentage  of 
casein  in  milk. — The  following-  results  illustrate,  in 
general,  the  variation  of  casein  in  the  milk  of  different 
breeds  of  cows : 


1O2     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


PERCENTAGE  OF  CASEIN  IN   MILK  OF  DIFFERENT  BREEDS 
OF  COWS 


Name  of  breed 

Holstein-Friesian 

Ayrshire 

American  Holderness.  .  .  . 

Shorthorn 

Devon 

Guernsey 

Jersey 


Per  cent  of  casein  in  milk 

2.20 

2.46 

2.63 

2.79 

3.10 

2.91 

3.03 


Influence  of  stage  of  lactation  on  the  percentage 
of  casein  in  milk. — We  will  first  present  results 
representing  the  average  of  about  100  lactation  periods 
of  individual  cows  and  then  the  results  representing 
work  done  at  the  New  York  experiment  station  in 
connection  with  cheese-factories  in  New  York  state, 
already  referred  to: 

VARIATION    OF   PERCENTAGE   OF    CASEIN    IN    MILK    WITH 
ADVANCE    OF    LACTATION 


Month  of  lactation 

Per  cent  of 
casein  in  milk 

Percentages  in  compari- 
son with  first  month 

1 

2  54 

100  0 

2  

2  42 

95  3 

3  

2  46 

96  8 

4 

2  52 

99  ? 

5  
6... 

2.61 
2  68 

102.8 
105  8 

7  . 

2  74 

1O8  O 

8... 

2  80 

1102 

9  

2  90 

1147 

10  

3  01 

11  

3  13 

123  2 

According  to  these  results,  the  percentage  of  casein 
decreases  in  the  second  month  of  lactation,  as  com- 
pared with  the  first,  and  then  begins  to  increase,  con- 
tinuing to  increase  month  by  month  to  the  end  of  the 
lactation  period.  The  behavior  very  closely  resembles 
that  of  fat. 


VARIATIONS    OF    MILK    CONSTITUENTS  163 

Turning-  now  to  the  results  obtained  at  cheese-fac- 
tories, we  have  the  following  data : 

VARIATION   OF   CASEIN    IN   CHEESE-FACTORY   MILK   WITH 
ADVANCE  OF  LACTATION 


Month 

Per  cent  of 
casein  in  milk 

Percentages  in  compari- 
son with  first  month 

April... 
May 

2.29 
2  34 

100.0 
102.2 

June  
July  
August  

2.47 
2.43 
2.39 

108.0 
106.1 
104.3 

September  
October  

2.55 
2.81 

111.3 
122.7 

In  the  foregoing  figures,  we  see  that  the  percentage 
of  casein  in  milk  increases  in  May  and  still  more  in 
June,  after  which  a  decrease  takes  place  in  July,  fol- 
lowed by  still  further  decrease  in  August.  There  is  a 
rapid  recovery  and  advance  during  September  and 
October.  The  cause  of  these  variations  will  be  con- 
sidered later. 

Influence  of  change  from  barn  to  pasture  upon 
the  percentage  of  casein. — Attention  has  already 
been  called  to  this  subject  in  relation  to  fat.  We  now 
give  corresponding  figures  for  casein.  During  the 
first  half  of  May,  the  milk  contained  2.25  per  cent  of 
casein  and  during  the  second  half  of  May,  2.45  per 
cent.  The  same  explanation  applies  as  in  the  case 
of  increase  of  fat. 

Influence  of  drouth  upon  the  percentage  of  casein 
in  milk. — During  a  time  of  severe  drouth  in  New 
York,  beginning  in  July  and  lasting  through  Au- 
gust, with  infrequent  and  insufficient  showers,  a 
marked  decrease  was  noticed  in  the  casein  of  the 
milk,  even  when  the  fat  was  increasing.  The  ana- 


[64     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

lytical  data  "are  given  later  on  p.  168.  Under  these 
conditions,  the  pasture  grasses  were  badly  burned, 
most  of  the  dairymen  were  without  supplementary 
supplies  of  food,  and  consequently  the  cows  suf- 
fered a  certain  degree  of  starvation.  The  changes 
in  composition  of  milk  were  accompanied  by  a 
severe  shrinkage  in  yield  of  milk.  Along  with  this 
impaired  condition  of  food  supply,  the  animals 
were  subjected  to  the  unfavorable  effects  coming 
from  excessive  heat  combined  with  annoyance  of 
flies.  Cheese-makers  often  complain  of  the  be- 
havior of  the  cheese  made  at  such  times,  without 
understanding  the  cause  of  their  difficulty.  The 
cheese  leaks  fat  badly,  does  not  press  together  well, 
and  does  not  stand  up  perfectly,  although  behaving 
properly  when  first  made.  There  is  also  noticed 
an  excessive  loss  of  fat  in  whey.  This  behavior  is 
due  to  an  abnormal  decrease  of  casein  in  relation 
to  fat,  so  that  the  milk  and  cheese  contain  an  ex- 
cess of  fat.  Cheese-makers  at  such  times  are  really 
dealing  with  milk  which  is  not  normal  factory  milk, 
but  which  is  like  normal  factory  milk  to  which  some 
cream  has  been  added.  The  extreme  heat  of  the 
weather,  which  causes  the  decrease  of  casein,  also 
makes  it  more  difficult  to  handle  such  milk  in  cheese- 
making.  In  the  twelfth  annual  report  of  the  Wiscon- 
sin experiment  station,  attention  is  called  to  a  similar 
condition. 

RELATION  OF  FAT  AND  CASEIN  IN  MILK 

As  we  shall  see  later  (p.  231),  the  relation  of 
fat  and  casein  in  milk  is  an  extremely  important 
one  in  connection  with  cheese-making.  At  this 


VARIATIONS    OF    MILK    CONSTITUENTS 


16' 


point  we  shall  call  attention  only  to  the  general 
relation  in  different  milks  and  to  the  conditions 
which  influence  this  relation,  leaving  the  various 
application  of  the  facts  to  later  chapters.  We  have 
already  noticed  the  percentages  of  fat  and  of  casein 
in  milk  and  some  of  the  conditions  which  cause 
variation.  We  now  come  to  consider  whether  fat 
and  casein  vary  alike ;  that  is,  whether  fat  and  casein 
have  the  same  relation  to  each  other  in  milk  under 
all  conditions.  We  will  consider  this  phase  of  the 
subject  under  the  following  divisions:  (i)  Individ- 
uality, (2)  breed,  (3)  stage  of  lactation,  and  (4)  fresh 
pastures  and  drouth. 

Influence  of  individuality  upon  relation  of  fat 
and  casein. — The  results  of  the  work  done  at  the 
New  York  experiment  station  and  elsewhere  have 
shown  that  the  relation  of  fat  and  casein  varies  greatly 
in  the  milk  of  different  individuals,  the  variation  being 
greatest,  of  course,  in  the  case  of  single  milk- 
ings.  This  fact  has  been  well  recognized  for  15 
years  or  more  and  is  too  familiar  even  to  need  illus- 
tration. 

Influence  of  breed  upon  relation  of  fat  and 
casein. — The  following  data  are  taken  from  those 
already  given  on  preceding  pages. 


Name  ef  breed 

Per  cent 
of  fat 

Per  cent 
of  casein 

Parts  of  casein  for 
one  part  of  fat 

3.26 

2.20 

Fat  :  Casein 
1:  0.67 

Ayrshire  
American  Holderness  

3.76 
4.01 
4.28 

2.46 
2.63 
2.79 

1:  0.65 
1:  0.66 
1:  0.65 

Devon  

4.89 

3.10 

l:  0.63 

Guernsey                              .  » 

5.38 

2.91 

1:  0.54 

Jersey  

5.78 

3.03 

1:  0.52 

166     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

It  is  seen  that  the  different  breeds  represented 
separate  into  two  general  groups  in  relation  to  the 
ratio  of  fat  to  casein.  In  the  case  of  the  first  five 
breeds  in  the  list,  this  ratio  does  not  vary  widely. 
The  milk  containing  least  fat  contains  the  largest 
amount  of  casein  in  relation  to  fat;  but,  even  though 
the  percentage  of  fat  in  the  case  of  this  group  in- 
creases to  4.89,  as  in  the  case  of  the  Devon  breed, 
the  ratio  of  casein  does  not  diminish  greatly.  The 
Guernsey  and  Jersey  breeds  constitute  the  second 
group,  the  fat  being  high  in  amount  but  the  casein 
relatively  low. 

Influence  of  stage  of  lactation  upon  the  relation 
of  fat  and  casein. — We  have  already  noticed  that 
the  percentage  of  fat  and  of  casein  increases  grad- 
ually and  quite  regularly  during  the  period  of  lacta- 
tion. We  will  now  consider  the  question  as  to 
whether  these  constituents  increase  in  the  same 
ratio. 


RELATION      OF     FAT     AND     CASEIN     DURING     LACTATION 
PERIOD 


Month  of  lactation 

Per  cent 
of  fat 

Per  cent 
of  casein 

Parts  of  casein  for 
one  part  of  fat 

1... 

4.30 
4.11 
4.21 
4.25 
4.38 
4.53 
4.57 
4.59 
4.67 
4.90 
5.07 

2.54 
2.42 
2.46 
2.52 
2.61 
2.68 
2.74 
2.84 
2.90 
3.01 
3.13 

Fa 

t  :  Casein 
0.59 
0.59 
0.58 
0.59 
0.60 
0.59 
0.60 
0.61 
0.62 
0.62 
0.62 

2  

3. 

4 

5  

6  

7 

8... 
9... 

10... 

11  

VARIATIONS    OF    MILK    CONSTITUENTS 


107 


These  results  show  a  remarkable  uniformity  in  the 
ratio  of  fat  to  casein  throughout  the  lactation  period. 
The  ratio  remains  quite  constant  for  seven  or  eight 
months  and  then  increases  slightly,  remaining  the 
same  during  the  rest  of  the  lactation  period. 

It  will  be  of  practical  interest  in  this  connection  to 
observe  what  the  relation  of  fat  and  casein  is  during 
the  season  in  the  case  of  the  mixed  milk  of  many 
herds  of  cows,  as  obtained  at  New  York  cheese  fac- 
tories 


RELATION     OF    FAT    AND     CASEIN     IN     CHEESE-FACTORY 
MILK  DURING  SEASON 


Month 

Per  cent 
of  fat 

Per  cent 
of  casein 

Parts  of  casein  for 
one  part  of  fat 

April 

3  43 

2  29 

Fat:  Casein 
1:  0  67 

May  
June 

3.58 
3  64 

2.34 
2  47 

1:0.65 
1:  0.68 

Tulv 

3  62 

2  43 

1:  0  67 

August  
September. 

3.84 
3  92 

2.39 
2  55 

1:0.62 
1:  0  65 

October  

4.23 

2.81 

It  0.66 

The  same  fairly  uniform  relation  holds  except  in 
the  case  of  the  month  of  August,  when  the  casein 
decreased  relative  to  fat.  It  is  interesting  to  notice 
how  closely  the  relation  of  fat  and  casein  in  cheese- 
factory  milk  agrees  with  that  of  the  Holstein-Friesian 
and  Ayrshire  types  as  given  in  the  table  on  p.  165. 
The  cheese-factory  cows  were  grade  Holsteins  and 
Ayrshires  to  a  considerable  extent 

Influence  of  fresh  pastures  and  of  drouth  upon 
the  relation  of  fat  and  casein  in  milk. — Using  the 
data  already  given,  we  have  the  following  tabular 


1 68     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

statement  in  regard  to  the  influence  of  turning  cows 
from  barn  into  pasture  about  the  middle  of  May : 


Per  cent 
of  fat 
in  milk 

Per  cent 
of  casein 
in  milk 

Parts  of  casein  for 
one  part  of  fat 

First  half  of  May  

3.46 

2.25 

Fat    Casein 
1    0.65 

Second  half  of  May  

3.70 

2.45 

1    0.66 

It  is  seen  that  under  the  conditions  indicated, 
the  fat  and  casein  maintain  a  relation  that  is  very 
uniform. 

Turning  now  to  data  obtained  during  a  summer 
when  extreme  drouth  prevailed  during  part  of  July 
and  all  of  August,  we  have  the  following  results : 


EFFECT  OF  DROUTH  UPON  RELATION  OF  FAT  TO  CASEIN 
IN  MILK 


Month 

Per  cent 
of  fat 

Per  cent 
of  casein 

Parts  of  casein  for 
one  part  of  fat 

May     . 

3.58 

2  40 

Fat:  Casein 
:  0.67 

3  59 

2  33 

•  0  65 

July  

August 

3.71 
4  04 

2.20 
2  26 

;  0.59 

:  o  56 

3  97 

2  47 

•  0  62 

October  

4.20 

2.69 

:  0.64 

These  .results  show,  for  cheese-factory  milks,  an 
abnormal  ratio  of  fat  and  casein  in  July,  which  was 
still  further  from  normal  in  August.  In  Septem- 
ber, when  abundant  rains  came  and  when,  in  addi- 
tion, dairymen  had  fodder  corn  to  supplement 
pastures  with,  the  ratio  became  more  nearly  nor- 
mal and  still  more  so  in  October.  From  the  stand- 
point of  practical  application,  these  facts  indicate 


VARIATIONS    OF    MILK    CONSTITUENTS  169 

the  necessity  for  dairymen  to  guard  against  the 
effects  of  drouth  by  making  provision  for  furnish- 
ing some  form  of  succulent  food  then.  At  such 
times,  there  is  an  enormous  loss  due  to  shrinkage 
in  yield  of  milk;  and,  in  cheese-making,  there  is  an 
abnormal  loss  of  fat  in  whey,  resulting  in  decreased 
yield  of  cheese  for  100  pounds  of  milk. 

THE  RELATION   OF  FAT   AND   CASEIN   IN 
CHEESE-FACTORY  MILK 

We  have  seen  that  the  relation  of  fat  and  casein 
is  a  variable  one,  the  variations  being  less  wide,  of 
course,  in  the  case  of  herd  milk  than  in  that  of 
individual  cows,  and  especially  of  single  milkings 
of  individuals.  But,  in  the  case  of  averages  of 
several  analyses  of  milk  -and  in  the  case  of  milk 
of  herds,  especially  when  cows  are  of  one  general 
type  in  respect  to  breed,  a  certain  degree  of  uniform- 
ity exists  in  the  relation  of  fat  to  casein.  In  New 
York  a  careful  study  was  made  of  the  milk  of  each 
of  50  different  herds  of  cheese-factory  cows  during 
one  season  (May  to  October),  and,  as  one  of  the 
results,  a  general  relation  was  noticed  between  the 
fat  and  casein.  In  general,  it  was  found  that  when 
the  fat  in  milk  increases  i.o  per  cent,  there  is  an 
average  increase  of  casein  amounting  to  0.4  per 
cent.  This  was  found  to  hold  quite  satisfactorily 
when  applied  in  case  of  ordinary  herd  milk  varying 
in  fat  content  from  3  to  4.5  per  cent  and,  in  many 
cases,  outside  of  these  limits.  In  milk  containing 
less  than  3  per  cent  of  fat,  the  casein  content  is 
usually  higher  in  relation  to  fat  than  in  milk  with 
more  than  3  per  cent  of  fat;  while,  in  the  case  of 


I7O     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

milk  containing  more  than  4.5  per  cent  of  fat,  the  ratio 
of  casein  to  fat  is  frequently  less  than  in  milk  con- 
taining less  than  4.5  per  cent  of  fat.  Starting  with 
milk  containing  an  average  of  3  per  cent  of  fat  and 
a  casein  content  of  2.1  per  cent,  milk  with  4  per  cent 
of  fat  was  found  to  contain  about  2.5  per  cent  of 
casein  on  an  average. 

RULE    FOR    CALCULATING    AMOUNT    OF 
CASEIN  IN  MILK 

On  the  basis  of  the  observed  general  relations  stated 
above,  the  following  formula  was  worked  out  for  cal- 
culating the  percentage  of  casein  in  milk  when  the  per 
cent  of  fat  is  known : 

(F — 3)Xo.4+2.i=per  cent  of  casein. 

F  equals  the  number  representing  the  per  cent  of  fat 
in  milk.  Expressed  as  a  rule,  we  have  the  following: 
From  the  number  representing  the  per  cent  of  fat 
in  milk  subtract  3 ;  multiply  the  result  by  0.4  and 
then  add  2.1.  The  formula  is  apt  to  give  results 
not  quite  up  to  the  actual  in  case  of  milk  produced 
after  the  eighth  or  ninth  month  of  lactation  period, 
when  the  casein  is  usually  a  little  greater  in  rela- 
tion to  fat  than  during  the  previous  stage  of  the 
lactation  period.  Applied  separately  to  the  milk 
of  50  herds  of  cows  during  the  factory  season,  the 
average  results  for  the  season  are  summarized  as 
follows :  ( i )  In  4  cases,  the  results  found  by  chemi- 
cal determination  were  identical  with  those  given 
by  calculation ;  (2)  in  36  cases,  the  results  by  cal- 
culation were  within  o.i  per  cent  of  those  obtained 
by  the  chemical  method;  (3)  in  8  cases  the  chemi- 
cal method  gave  o.i  to  0.2  per  cent  less  than  the 


VARIATIONS    OF    MILK    CONSTITUENTS  17! 

calculated  amount;  (4)  in  2  cases  the  calculated  per 
cent  exceeded  that  found  by  the  chemical  method  to 
the  extent  of  0.23  and  0.25  per  cent.  It  is  thus  seen 
that,  taking  the  entire  season's  average,  80  per  cent 
of  the  results  by  the  method  of  calculation  differed 
from  those  obtained  with  the  chemical  method  by 
less  than  o.i  per  cent.  The  results  given  below 
represent  the  application  of  the  formula  in  case  of  herd 
milk : 


Per  cent  of  fat  Per  cent  of  casein  in  milk,  as  found  by 

in  milk  (1)  (2) 

Chemical  method  Calculation 

3.25  2.38  2.20 

3.31  2.19  2.22 

3.42  2.27  2.27 

3.52  2.30  2.30 

3.55  2.34  2.32 

3.55  2.18  2.32 

3.63  2.45  2.35 

3.63  2.33  2.35 

3.71  2.29  2.38 

3.71  2.48  2.38 

3.71  2.35  2.38 

3.84  2.44  2.44 

3.84  2.37  2.44 

3.92  2.42  2.47 

4.00  2.53  2.50 

4.14  2.50  2.56 

425  2.51  2.60 

4.31  2.37  2.62 


For  ordinary  purposes,  where  the  strictest  accu- 
racy is  not  required,  the  rule  can  be  used  with  quite 
satisfactory  results,  when  applied  to  herd  milks 
within  the  limits  specified,  and  most  of  our  cheese- 
factory  milks  come  within  these  limits.  Of  course, 
it  is  readily  recognized  that,  when  very  accurate 
results  are  necessary,  only  a  direct  determination 
of  casein  by  an  accurate  method  can  suffice  for  the 
purpose ;  and,  by  an  accurate  method,  is  meant  one 
which  can  be  relied  upon  to  give  results  within  one- 
tenth  of  one  per  cent  of  the  truth. 


1^2     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

AMOUNT  OF  FAT  AND    CASEIN  IN  ORDI- 
NARY FACTORY  MILK 

In  the  case  of  ordinary  cheese-factory  milk,  we  may 
expect  to  find  the  fat  and  casein  run  somewhat  as 
follows : 

•        Per  cent  of  fat  Per  cent  of  casein  RatA°  °^ 

in  milk  in  milk  Fat:  Casein 

3.00  2.10  1:0.70 

325  2.20  1:0.68 

3.50  2.30  1:0.66 

3.75  2.40  1:0.64 

4.00  2.50  1:0.62 

4.25  2.60  1:0.61 

4.50  2.70  1:0.60 

5.00  2.90  1:0.59 

RELATION  OF  CASEIN  AND  ALBUMIN  IN 
MILK 

It  is  a  matter  of  practical  interest  in  connection 
with  cheese-making  to  know  whether,  in  milk  with 
a  high  percentage  of  casein,  there  is  also  a  propor- 
tionally high  percentage  of  albumin.  The  higher 
the  casein,  relative  to  albumin,  the  greater  is  the 
proportion  of  cheese-producing  constituents.  We 
will  study  this  question  in  relation  to  (i)  breed  and 
(2)  stage  of  lactation.  It  should  be  stated  that 
albumin,  as  here  used,  includes  all  the  proteins  of  the 
milk  other  than  casein. 

In  studying  the  results,  it  is  noticeable  that,  in 
general,  in  the  case  of  milk  containing  a  low  per- 
centage of  fat  (p.  165),  the  albumin  forms  a  larger 
proportion  of  the  proteins  than  in  case  of  milk  con- 
taining a  high  percentage  of  fat,  when  we  compare 
the  milk  of  different  breeds  of  cows  under  corre- 
sponding conditions.  Also,  in  milks  low  in  fat,  the 
casein  forms  a  smaller  proportion  of  the  proteins 


VARIATIONS    OF    MILK    CONSTITUENTS 


173 


INFLUENCE  OF  BREED   UPON   THE  RELATION   OF   CASEIN 
AND  ALBUMIN 


Per  cent 

Per  cent 

Name  of  breed 

of 
proteins 
(casein 
and 

Per  cent 
of 
casein 

Per  cent 
of 
albumin 

Parts  of  casein 
for  one  part 
of  albumin 

of  total 
proteins 
inform 
of 

albumin) 

casein 

Holstein-Friesian.  .  .  . 

2.84 

2.20 

0.64 

Albumin'.  Casein 
1       3.4 

77.5 

Ayrshire.  . 

3.07 

2.46 

0.61 

1       4.0 

80.1 

American  Holderness 

3.32 

2.63 

0.69 

1       3.8 

79.2 

Shorthorn  

3.43 

2.79 

0.64 

1       4.5      - 

81.3 

Devon  

3.93 

3.10 

0.83 

1       3.7 

78.9 

Guernsey             .    . 

3  56 

2  91 

0  65 

1       4.5 

81.7 

Jersey  

3.68 

3.03 

0.65 

1      4.7 

82.3 

than  in  "case  of  milks  higher  in  fat.  Thus,  in  the 
milk  of  Holstein-Friesian  cows,  we  have  the  least 
amount  of  fat  (3.26  per  cent),  and  the  casein  forms 
a  smaller  part  (77.5  per  cent),  and  the  albumin  a 
larger  part  (22.5  per  cent),  of  the  proteins  than  in 
case  of  any  other  breed  under  discussion.  In  the 
case  of  Guernsey  and  Jersey  milk,  in  which  the  fat 
content  is  highest,  the  proportion  of  casein  to  pro- 
teins is  greatest  (about  82  per  cent),  while  it  is  least 
for  albumin  (about  18  per  cent).  In  its  practical 
application,  these  results  mean  that,  in  the  case  of 
Jersey  and  Guernsey  milk,  a  larger  proportion  of  the 
proteins  is  utilized  in  cheese-making  and  a  smaller 
proportion  is  lost  in  whey. 

The  relation  of  casein  and  albumin,  as  shown  by 
the  following  data,  is  remarkably  uniform  during 
the  first  eight  or  nine  months  of  lactation,  varying 
between  4.1  and  4.2  parts  of  casein  for  one  of 
albumin ;  or,  stated  in  another  way,  the  percentage 
of  total  proteins  in  the  form  of  casein  varied  from 
80.3  to  80.9  and,  in  the  form  of  albumin,  from  19.1 


1/4     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


INFLUENCE   OF    STAGE   OF    LACTATION    UPON    THE    RELA- 
TION OF  CASEIN  AND  ALBUMIN 


Per  cent 

Parts  of  casein 

Per  cent  of 

Month 

of  Proteins 

Per  cent 

Per  cent 

for  one  part 

total 

of 

(casein  and 

of 

of 

of  albumin 

proteins  in 

lactation 

albumin) 

casein 

albumin 

Albumin:  Casein 

form  of 

casein 

1  

3.16 

2.54 

0.62 

1       4.1 

80.4 

2  

2.99 

2.42 

0.57 

4.2 

80.9 

3  

3.04 

2.46 

0.58 

4.2 

80.9 

4  

3.13 

2.52 

0.61 

4.1 

80.5 

5  

3.25 

2.61 

0.64 

4.1 

80.3 

6  

3.33 

2.68 

0.65 

4.1 

80.5 

7  

3.40 

2.74 

0.66 

4.2 

80.6 

8  

3.47 

2.80 

0.67 

4.2 

80.7 

9..  . 

3  57 

2.90 

0.67 

4.3 

81.2 

10 

3.79 

3.01 

0.78 

3.9 

79  A 

11            

4  04 

3.13 

0.91 

:     3!4 

77  5 

to  19.7.  After  the  ninth  month,  the  albumin  in- 
creases relative  to  casein,  the  increase  being  very 
marked  in  the  two  closing  months  of  the  lactation 
periods  studied. 

In  the  case  of  the  mixed  milk  of  numerous  herds 
of  cheese-factory  cows,  we  have  the  following  re- 
sults : 


Per  cent 

Per  cent 

Parts  of  casein 

of  total 

Month  

of  protein 
(casein  and 

Per  cent 

of 

Per  cent 
of 

for  one  part 
of  albumin 

proteins  in 
form  of 

albumin) 

casein 

albumin 

casein 

April  

2.81 

2.29 

0.52 

Albumin:  Casein 
1:     4.4 

81  5 

May  

3.02 

2.34 

0.68 

1:     3.4 

77.5 

June.  . 

3  24 

2  47 

0  77 

1  •     3  ? 

July- 

3  07 

2  43 

0  64 

August  
September.  . 
October  

3.02 
3.20 
3.55 

2.39 
2.55 
2.81 

0.63 
0.65 
0.74 

1:     3.8 
1:     3.9 
1:     3.8 

79.1 
79.7 
79.2 

The   proportion    of   casein    in    relation    to    albumin 
decreases    until    July,    when    a    marked    increase    oc- 


VARIATIONS     OF     MILK     CONSTITUENTS 


175 


curs;  and  then  the  ratio  remains  uniform  during  the 
rest  of  the  season,  which  extends  approximately 
through  the  seventh  or  eighth  month  of  lactation. 

The  general  statement  has  been  prominently  cur- 
rent in  literature  to  the  effect  that  casein  and  albumin 
are  present  in  cow's  milk  in  very  constant  relative  pro- 
portions, the  amount  of  casein  being  five  times  that  of 
albumin.  In  the  case  of  herd  milks,  we  have  found 
casein  varying  all  the  way  from  2.6  to  5.6  parts  for 
one  part  of  albumin.  In  single  milkings  of  individual 
cows,  the  variations  are  considerably  wider. 

AVERAGE  COMPOSITION  FACTORY  MILK 

The  following  figures  represent  the  average 
monthly  composition  of  milk  as  obtained  at  cheese- 
factories  in  New  York  state.  These  data  repre- 
sent the  work  of  several  seasons  and  are  taken 
from  the  records  of  the  New  York  experiment 
station : 


Month 

Solids 

Fat 

Casein 

Albumin 

Sugar 
ash.  etc. 

April 

11  98 

3  43 

2  29 

0  52 

5.74 

May" 

12  43 

3  58 

2  34 

C  68 

5  83 

June  
Tulv 

12.64 
12  52 

3.64 
3  62 

2.47 
2  43 

0.77 
0.64 

5.76 
5.83 

August  
September  
October 

12.65 
12.86 
13  50 

3.84 
3.98 
4  23 

2.39 
2.55 
2  81 

0.63 
0.65 
0.74 

5.79 
5.68 
5.72 

Average  

12.67 

3.75 

2.46 

0.68 

5.78 

The  following  figures  show  the  extreme  variations 
in  composition  of  cheese-factory  milk  during  the 
season : 


I/O     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


Lowest 

per  cent 

Highest 
per  cent 

Solids   .                         .......                         ... 

11  47 

13  91 

Fat 

3  04 

4  60 

Casein.  
Albumin                                                                 

1.93 
0  47 

3.00 
0  88 

Sugar    ash    etc 

5  32 

537 

For  a  more  general  and,  in  some  .respects,  more  com- 
plete discussion  of  the  chemistry  of  milk,  the  reader 
is  referred  to  "Modern  Methods  of  Testing  Milk  and 
Milk  Products,"  published  by  Orange  Judd  Company. 


CHAPTER  XVI 

Functions  of  Milk  Constituents  in 
Cheese-Making 

Having  considered  the  properties  and  amounts  of 
different  constituents  in  milk  in  connection  with 
cheese-making,  it  -is  a  matter  of  interest  to  notice  what 
particular  part  each  performs  in  the  process  or  what 
particular  contribution  of  value  each  makes  to  the 
finished  product.  It  will  be  found  that  each  con- 
stituent has  a  value  peculiar  to  itself  in  relation  to 
cheese  and  the  process  of  cheese-making. 

MILK-FAT 

'-* 

Milk- fat  is  the  object  of  solicitous  care  on  the 
part  of  the  intelligent  cheese-maker,  and  its  pecu- 
liarities have  much  to  do  with  certain  details  of 
the  cheese-making  process.  Its  part  in  the  actual 
process  of  cheese-making  is,  however,  a  passive 
rather  than  an  active  one,  since  the  details  of  the 
operations  are  governed,  to  a  considerable  extent, 
by  the  aim  of  retaining  as  much  milk-fat  as  pos- 
sible in  the  cheese  and  losing  the  smallest  possible 
amount  in  whey.  The  reasons  for  keeping  milk-fat 
in  cheese  are  twofold,  (i)  on  account  of  its  influence 
on  the  yield  of  cheese  and  (2)  on  account  of  its  effect 
upon  the  quality  of  the  cheese. 

So  far  as  we  know  at  present,  milk-fat  contributes 
little  or  nothing  to  the  aroma  of  normal  cheddar 

177 


178      SCIENCE   AND    PRACTICE   OF    CHEESE-MAKING 

cheese ;  but  its  chief  functions,  in  relation  to  quality  of 
cheese,  appear  to  be  to  give  (i)  a  characteristic  mel- 
lowness of  body,  (2)  smoothness  of  feeling,  (3)  rich- 
ness and  delicacy  of  taste,  apart  from  cheese  flavor 
proper,  and  (4),  in  general,  palatability.  No  other 
constituent  can  take  its  place  satisfactorily  in  perform- 
ing any  of  these  offices.  Of  course,  the  high  value  of 
milk-fat  as  a  food  should  not  be  lost  sight  of,  but  this 
does  not  necessarily  enter  into  the  question  of  quality 
of  cheese  as  affected  by  the  presence  of  fat.  The 
peculiar  and  exclusive  function  of  milk-fat  in  giving  to 
cheese  certain  desirable  qualities  can  be  well  appre- 
ciated by  comparing  different  kinds  of  cheese,  equally 
well  made  and  differing  only  in  the  percentage  of  fat 
contained  in  them,  as,  for  example,  cheese  made  from 
normal  milk  containing  added  cream,  cheese  made  from 
normal  Jersey  milk,  cheese  made  from  Holstein- 
Friesian  milk,  and  cheese  made  from  milk  skimmed 
in  varying  degrees,  down  to  separator  skim-milk 
cheese. 

The  relation  of  fat  to  yield  of  cheese  will  be  con- 
sidered in  detail  in  the  next  chapter. 

MILK-CASEIN 

Casein  is  the  constituent  of  milk  which,  on  ac- 
count of  its  peculiar  action  toward  rennet-extract 
solutions,  makes  possible  the  manufacture  of  ched- 
dar  and  many  other  kinds  of  cheese.  In  the  pro- 
cess of  cheese-making,  it  performs  two  specific 
functions:  (i)  In  its  solidification,  its  first  work  is 
to  imprison  the  fat-globules  in  the  curd  and  then 
continue  to  hold  them  as  firmly  as  possible  through- 
out the  manipulations  of  cheese-making.  (2)  Its 


FUNCTIONS    OF    MILK    CONSTITUENTS  179 

second  function  is  to  retain  whey  in  the  curd  in 
desired  amounts,  while,  at  the  same  time,  permit- 
ting superfluous  whey  to  escape  from  the  mass  of 
curd.  The  power  of  casein  to  hold  moisture  is 
somewhat  like  that  of  a  sponge.  Special  experi- 
ments at  the  New  York  experiment  station  have 
shown  that  one  pound  of  dry  casein  can  easily 
absorb  and  hold  about  one  pound  and  a  quarter  of 
water.  Fat  has,  of  course,  comparatively  little 
water-holding  power,  so  that  this  function  falls 
almost  entirely  on  casein.  It  is  obvious  that  this 
special  work  can  be  done  by  no  other  constituent 
of  milk,  and  thus  casein  is  recognized  as  the  water- 
holder  in  cheese. 

In  the  finished  product,  casein,  or  rather,  the 
compound  formed  from  it,  performs  two  important 
and  peculiar  functions,  (i)  It  gives  to  the  cheese 
firmness  and  solidity  of  body  under  a  wide  range 
of  temperature,  conditions  which  are  requisite  for 
its  keeping  and  convenient  handling.  The  casein- 
derived  product  in  reality  constitutes  the  firm 
framework  or  skeleton  which  gives  permanence  to 
the  form  of  the  cheese.  (2)  It  furnishes  the  protein 
material  in  which,  it  is  believed,  take  place  those 
changes  that  result  in  characteristic  cheese  flavors, 
while,  at  the  same  time,  it  is  converted  into  soluble, 
nutritive  compounds,  which  add  largely  to  the  value 
of  the  cheese  as  food.  The  peculiar  properties  of 
casein  when  made  into  cheese  are  such  that  its 
presence  in  excess  in  relation  to  fat  or  moisture 
causes  serious  deterioration  in  some  of  the  proper- 
ties of  the  cheese.  For  instance,  when  an  excess  of 
casein  is  used,  as  in  the  case  of  skim-milk  cheese, 


i8O     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

the  .desirable  firmness  of  body  becomes  objectionable 
hardness,  unless  the  conditions  of  manufacture  are 
so  modified  as  to  hold  more  whey  in  cheese,  in  which 
case  objectionable  properties  of  another  kind  are  apt 
to  result. 

WATER 

As  we  shall  see  later,  when  we  come  to  study 
the  composition  of  cheese,  water  is  one  of  the  most 
prominent  constituents  in  amount.  We  have  al- 
ready indicated  why  the  amount  of  water  in  normal 
milk  has  little  interest  in  connection  with  cheese- 
making,  but  its  presence  in  cheese  is  of  great 
interest  and  the  problem  of  its  control  in  the  cheese- 
making  process  is  one  of  the  highest  importance. 
Water  performs  two  chief  functions  in  cheese: 
(i)  Somewhat  like  fat,  but  in  a  much  less  satisfactory 
way,  it  influences  the  character  of  the  body  in  cheese, 
imparting  smoothness  and  a  certain  degree  of  mellow- 
ness, and  (2)  it  furnishes  suitable  conditions  for  the 
work  of  those  agents  which  change  insoluble  cheese 
proteins  into  soluble  forms  (p.  353). 

In  performing  the  first  of  these  functions,  water, 
therefore,  supplements  the  work  of  fat,  but  cannot 
take  its  place  in  imparting  richness  and  delicacy  of 
taste.  In  the  manufacture  of  skim-milk  cheese,  an 
effort  is  usually  made  to  imitate  the  mellowness  of 
body  characteristic  of  a  cheese  made  from  normal  milk, 
which  is  due  to  fat,  by  holding  in  the  cheese  a  large 
amount  of  moisture.  In  illustration  of  this  fact, 
we  have  examined  cheese  containing  over  50  per 
cent  of  water,  the  cheese  having  been  made  from 
separator  skim-milk.  Unless  this  large  amount  of 


FUNCTIONS    OF    MILK    CONSTITUENTS  l8l 

moisture  is  retained,  the  cheese  is  hard,  tough  and 
unpalatable.  Even  in  cheese  made  from  normal 
milk,  the  body  becomes  dry  and  mealy  or  crumbly, 
if  the  amount  of  moisture  falls  much  below  30  per 
cent.  The  higher  the  fat  content  of  the  cheese,  the 
lower  can  be  the  amount  of  water  without  impair- 
ing the  body  of  the  cheese.  The  temptation  is  often 
strong  in  making  cheese  to  incorporate  5  per  cent 
or  more  of  moisture  beyond  the  usual  amount,  be- 
cause water  is  the  only  cheese  constituent  that  can 
be  had  free  of  cost.  The  aim  of  cheese-makers 
should  be  so  to  control  conditions  of  manufacture  as 
to  retain  in  cheese  only  the  proper  amount  of  moisture 
(p.  382). 

We  have  already  stated  that  another  function  of 
water  in  cheese  is  to  furnish  conditions  suitable  for 
the  work  of  those  agents  which  convert  insoluble 
cheese  proteins  into  soluble  forms.  If  the  amount 
of  water  is  below  a  certain  limit,  25  to  27  per  cent, 
these  changes  do  not  take  place  and  the  cheese  fails 
to  become  edible. 

Some  erroneously  think  that  water  in  cheese  is 
of  a  peculiar  kind  and  possesses  a  special  value  as 
such, — that  it  is  really  different  from  water  as  we 
find  it  elsewhere.  One  writer  goes  so  far  as  to 
speak  of  the  water  in  cheese  as  "natural  water," 
"natural  moisture,"  as  if  it  possessed  some  unusual 
virtue  because  it  had  gone  through  a  cow  and 
formed  a  part  of  milk  before  going  into  cheese  as 
"natural"  water.  Such  a  belief  is  quite  without 
foundation,  because  the  water  in  cheese  can  be 
easily  separated  from  the  cheese  and  examined  and 
is  known  to  possess  the  usual  composition  of  water 


182     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

wherever  we  find  it.  It  is  true,  of  course,  that  the 
presence  of  water  in  cheese  is  masked  by  the  casein 
and  fat  and  one  of  the  aims  of  the  cheese-maker  is 
to  conceal  it  thus  as  completely  as  possible;  but  this 
fact  has  no  bearing  on  the  composition  or  character 
of  the  water  itself. 

MILK-SUGAR 

The  only  function  milk-sugar  appears  to  per- 
form in  the  process  of  cheese-making  is  to  fur- 
nish material  for  making  lactic  acid.  Lactic  acid 
does  not  remain  in  milk  as  free  or  uncombined 
acid,  but,  as  fast  as  formed,  it  acts  upon  some  of  the 
salts  of  the  milk,  especially  insoluble  calcium  phos- 
phate, combining  with  a  portion  of  the  calcium  and 
forming  calcium  lactate  and  soluble  or  acid  calcium 
phosphate,  an  acid  salt.  There  are  probably  other 
salts  in  milk  acted  upon,  about  the  details  of  which 
we  have  not  yet  obtained  complete  knowledge.  These 
soluble  calcium  salts  (calcium  lactate,  and  acid  cal- 
cium phosphate,  including  probably  also  acid  calcium 
citrate)  resulting  from  the  action  of  acid  furnished 
by  the  fermentation  of  milk-sugar,  perform  several 
functions  in  the  cheese-making  process. 

(i)  These  soluble  calcium  salts  favor  the  rapid- 
ity and  completeness  of  the  action  of  rennet-extract 
in  coagulating  milk;  in  fact,  their  presence  in  cer- 
tain amounts  is  essential  to  the  action  of  the  ren- 
net-enzym.  Now,  while  the  immediate  object  of 
ripening  milk  in  cheese-making  is  to  convert  milk- 
sugar  into  lactic  acid,  the  real  purpose  is  the  forma- 
tion of  soluble  calcium  salts  to  hasten  rennet 
coagulation. 


FUNCTIONS   OF    MILK    CONSTITUENTS  183 

(2)  The   soluble  calcium   salts   probably  perform 
some    work    in    assisting   in    the    contraction    of   the 
curd.       After  the  curd  is  formed  in  the  cheese-vat, 
the   milk-sugar    remains   in   the   coagulated   mass   at 
first,    but    gradually    passes    out    in    solution    as    the 
whey  exudes  from  the  pieces  of  curd.     The  amount 
of   sugar   remaining   in    the    curd   is    much   reduced, 
but  the   formation  of  lactic  acid  continues,  thus  in- 
creasing the  amount  of  calcium  lactate,  acid  calcium 
phosphate,  acid   calcium  citrate,   etc.     Cheese-makers 
speak  of  acid  in  curd  frequently  when  they  really  mean 
whey  or,  more  strictly,  milk-sugar  contained  in  whey 
within  the  pieces  of  curd  and  ready  to  form  lactic  acid 
sooner  or  later. 

(3)  The    formation    of    soluble    calcium    salts    is 
probably    also    more    or    less    intimately    connected 
with  the  changes  in  the  curd  during  the  cheddaring 
process,  when  the  grain  or  texture  rapidly  changes, 
finally   resembling   the   fiber   of  the   cooked   meat  on 
a  chicken's  breast  and   when  the  curd   develops   the 
characteristic    plastic    properties    exhibited    by    form- 
ing  long,    silky   strings,    when   brought   into    contact 
with  a  hot  iron.     This  change  appears  to  depend  upon 
the  conversion  of  paracasein  into  a  substance  soluble 
in  brine  solution  (p.  147). 

The  conversion  of  milk-sugar  into  lactic  acid, 
with  consequent  formation  of  increasing  quantities 
of  soluble  calcium  salts,  continues  quite  rapidly 
throughout  the  cheese-making  process  and  also  in 
the  press  and  still  later  in  the  cheese.  Under  ordi- 
nary conditions,  the  last  trace  of  milk-sugar  disap- 
pears in  about  two  weeks  after  the  cheese  is  made. 
But,  throughout  the  process  of  cheese-making,  when 


184     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


: 


the  conditions  are  normal,  there  is  never  enough  sugar 
converted  into  lactic  acid  to  combine  with  all  the  avail- 
able calcium  in  cheese  and  form  free  lactic  acid;  and 
there  is  never  left  in  the  cheese,  under  normal  con- 
ditions, enough  milk-sugar  to  form  free  acid.  There- 
fore, in  normal  cheddar  cheese,  we  never  have  free 
lactic  acid. 

When  a  large  amount  of  whey  is  left  in  cheese, 
that  means  a  corresponding  amount  of  milk-sugar, 
a  correspondingly  large  amount  of  acid,  with  forma- 
tion of  increased  amounts  of  calcium  salts,  resulting 
in  the  production  of  what  is  known  as  "acid"  or  "sour" 
cheese. 

(4)  Another    well-recognized    function    of    milk- 
sugar,  as  a  result  of  the  formation  of  lactic  acid  and 
acid  salts   in   milk,   is  the   prevention   of  the   growth 
of    other    micro-organisms    which    are    often    present 
in  milk  and  give  rise  to   forms  of  fermentation  that 
interfere     seriously     with     the    production     of    good 
cheese,    such    as    the    micro-organisms    that    produce 
gases,  ill-smelling  compounds,  etc.     It  is  known  that, 
if  the  acid   salts   and   milk-sugar   in   cheese-curd  are 
removed,    as    is    done    in    the    case    of   the    "soaked- 
curd"  process  (p.  57),  the  resulting  cheese  undergoes 
abnormal  changes  in  ripening,  forming  products  that 
are  putrefactive  in  character  and  which  seriously  im- 
pair or  destroy  the  value  of  the  cheese  as  food. 

( 5 )  It  may  be  found  that  the  fermentation  products 
of  milk-sugar  are  more  intimately  associated  with  the 
development  of  cheese  flavor  than  has  been  previously 
thought. 

SALTS  OF  MILK 

The  salts  of  milk  appear,  as  already  explained  in 
connection  with  the  functions  of  milk-sugar,  to 


FUNCTIONS  OF   MILK   CONSTITUENTS  185 

depend  largely  for  the  active  part  which  they  take 
in  cheese-making  upon  the  presence  of  lactic  acid, 
by  which  insoluble  calcium  salts  are  converted  into 
soluble  forms,  especially  soluble  calcium  phosphate. 
When  we  determine  the  acidity  of  whey  at  various 
stages  of  the  operations  of  cheese-making,  we  are 
really  measuring  directly  the  formation  of  acid  com- 
pounds, which  furnish,  of  course,  a  measure  of  the 
amount  of  lactic  acid  that  has  been  formed. 

It  has  been  noticed  that,  when  in  the  making  of 
cheese  a  higher  degree  of  acidity  is  produced,  while 
the  curd  is  still  in  the  whey,  that  the  amount  of  ash 
in  the  cheese  is  less  than  when  so  much  acid  is  not 
formed.  This  is  in  accordance  with  what  one  would 
expect,  since  the  more  rapidly  the  insoluble  calcium 
salts  are  dissolved  while  the  curd  is  in  the  cheese-vat, 
the  larger  is  the  amount  of  soluble  salts  going  into 
the  whey. 


CHAPTER  XVII 

Milk  Constituents  and  Yield  of  Cheese 

The  relation  of  the  composition  of  milk  to  yield 
of  cheese  is  a  subject  of  the  highest  practical  in- 
terest and  importance  to  cheese-makers.  Compara- 
tively little  was  known  about  it  previous  to  1892, 
because  attention  had  been  completely  absorbed  by 
the  merely  mechanical  methods  of  cheese-making. 
We  were  completely  in  the  dark  in  regard  to  such 
fundamental  facts  as  the  relation  of  fat  and  casein 
in  milk  to  yield  of  cheese,  the  character  and  extent 
of  losses  of  milk  constituents  in  cheese-making, 
their  causes  and  remedies,  and,  in  general,  the  de- 
tailed relations  existing  between  cheese  and  the 
material  from  which  it  is  made.  So  profound  was 
the  ignorance  regarding  milk  constituents  and  their 
relation  to  yield  of  cheese  that  it  was  very  gener- 
ally believed  that  the  same  amount  of  cheese  was 
made  from  100  pounds  of  milk  in  the  case  of  the 
milks  of  different  herds.  We  now  have  on  hand  an 
immense  mass  of  data,  the  accumulated  results  of 
the  investigation  work  of  our  American  experiment 
stations,  and  these  data  enable  us  to  reach  very 
definite,  positive  and  final  conclusions. 

The  amount  of  fresh  or  green  cheese  produced  by 
100  pounds  of  milk  depends  upon  three  factors: 

1 i )  The  percentage  of  fat  and  of  casein  in  milk. 

(2)  The  percentage  of  fat  and  of  casein  lost  in 
cheese-making. 

186 


MILK   AND    YIELD   OF    CHEESE  187 

(3)     The  amount  of  whey  retained  in  cheese. 

THE  RELATION  OF  FAT  AND  OF  CASEIN 
TO  YIELD  OF  CHEESE 

Those  constituents  of  the  milk  that  are  insoluble 
and  are  present  in  suspension  as  solids  or  in  emul- 
sion, those  that  can  be,  for  the  most  part,  mechan- 
ically held  by  the  coagulated  casein,  furnish  the 
solid  materials  for  cheese.  They  are:  (i)  Milk- 
fat;  (2)  milk-casein;  and  (3)  insoluble  phosphates. 
The  fat  and  casein  constitute  so  large  a  proportion 
of  these  cheese-producing  solids  of  milk  that  we 
should  not  be  far  from  the  truth  in  saying  that 
only  these  two  constituents  of  normal  milk  are 
prominent  in  determining  the  yield  of  cheese.  These 
two  constituents  of  milk  form  over  90  per  cent  of 
the  solid  portion  of  cheese  (cheese-solids)  ;  the  only 
other  solids  in  cheese  are  comparatively  small  in 
amount,  consisting  essentially  (i)  of  the  calcium 
salts  of  phosphoric,  lactic  and  citric  acids;  (2)  of  the 
salt  added  in  cheese-making;  (3)  of  a  small  amount 
of  milk-albumin;  and  (4)  of  some  milk-sugar,  which 
mostly  disappears  in  a  few  days. 

The  yield  of  cheese  from  milk  varies  as  the 
amount  of  fat  and  casein  in  milk  vary,  provided  the 
conditions  of  cheese-making  are  the  same,  includ- 
ing under  these  conditions  the  quality  of  the  milk 
with  reference  to  cleanliness  (bacterial  content),  (p. 
4).  As  a  rule,  when  the  percentage  of  fat  in  milk 
increases,  the  percentage  of  casein  also  increases  (p. 
169)  and  the  yield  of  cheese  increases  in  proportion 
to  the  increase  of  fat  and  casein.  At  this  point,  the 


l88     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

questions  naturally  arise:  How  much  does  milk-fat 
contribute  to  cheese  yield?  How  much  does  milk- 
casein  contribute  to  cheese  yield?  This  at  once 
brings  us  to  a  consideration  of  the  losses  of  these 
constituents  in  the  process  of  cheese-making. 

THE  LOSSES  OF  MILK  CONSTITUENTS  IN 
CHEESE-MAKING 

In  transferring  fat  and  casein  from  milk  into 
cheese  through  the  operations  of  cheese-making, 
certain  amounts  of  these  constituents  are  unavoid- 
ably lost  in  the  escaping  whey  and  do  not,  conse- 
quently, contribute  to  the  yield  of  cheese.  It  is 
obvious,  therefore,  that  the  cheese  yield  from  a 
given  amount  of  milk  is  dependent,  to  some  extent, 
upon  the  degree  of  completeness  with  which  the 
fat  and  casein  of  milk  are  worked  into  cheese;  that 
is,  upon  the  degree  of  success  experienced  in  re- 
ducing these  losses  to  a  minimum.  It  is  very  im- 
portant, then,  that  in  studying  the  relation  of  milk 
constituents  to  yield  of  cheese,  we  learn  something 
of  the  extent  to  which  such  losses  are  found  in  actual 
experience,  the  conditions  responsible  for  these  losses, 
and  the  means  by  which  they  can  be  made  as  small 
as  possible. 

The  losses  of  milk-fat  in  cheese-making. — Less 
than  20  years  ago  cheese-makers  almost  universally 
believed  that  all  fat  in  milk  above  3.5  or  4.0  per 
cent  must  go  into  whey  and  not  into  cheese.  Breed- 
ers of  cows  giving  milk  low  in  fat  content  openly 
declared,  and  without  contradiction,  that  only  cows 
of  this  type  could  be  suitable  for  profitable  cheese- 
making,  because  it  was  impossible  to  transfer  the 
extra  milk-fat  into  cheese  when  milk  contained  over 


MILK   AND  YIELD  OF   CHEESE  189 

3.5  per  cent.  This  question  has  been  studied  ex- 
haustively at  the  New  York  experiment  station 
under  a  great  variety  of  conditions,  including  extended 
investigations  in  case  of  actual  operations  in  many 
different  cheese-factories.  The  following  institu- 
tions have  contributed  additional,  though  less  exten- 
sive, data,  which  fully  confirm  the  results  obtained 
in  New  York:  The  experiment  stations  of  Wiscon- 
sin, Minnesota,  Iowa,  Vermont,  Utah  and  the  Ontario 
agricultural  college.  Probably  much  unpublished  work 
has  been  done  elsewhere. 

Taking  the  results  of  extended  study  under 
cheese-factory  conditions,  we  have  found  that  the 
amount  of  fat  lost  for  100  pounds  of  milk  varies 
from  0.20  to  0.50  pound  (equivalent  to  0.22  to  0.55 
per  cent  of  fat  in  whey),  the  average  being  0.33 
pound  (equivalent  to  0.36  per  cent  of  fat  in  whey). 
This  amounts  to  about  9  per  cent  of  the  fat  in  the 
milk.  In  one  factory  which  was  under  observation 
for  an  entire  season,  the  loss  of  fat  for  100  pounds 
of  milk  varied  from  0.20  to  0.36,  and  averaged  0.25, 
pound  (equivalent  to  0.22,  0.40  and  0.27  per  cent 
of  fat  in  whey).  This  average  is  equivalent  to  7 
per  cent  of  the  fat  in  the  milk.  In  another  factory, 
which  was  under  observation  at  the  same  time, 
the  amount  of  fat  lost  varied  from  0.26  to  0.50, 
and  averaged  0.37,  pound  (equivalent  to  0.29,  0.55 
and  0.42  per  cent  of  fat  in  whey).  The  average 
loss  in  this  case  is  nearly  10  per  cent  of  the  fat  in 
the  milk.  In  some  cases,  losses  of  fat  under  0.20 
pound  have  been  reported,  but  such  experience  is 
not  common  in  most  cheese-factories.  In  general, 
it  may  be  said  that  really  efficient  work  is  not 


I9O     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


being  done  by  a  cheese-maker  when  the  percentage 
of  fat  in  whey  exceeds  0.30,  if  the  milk  furnished 
is  in  good  condition  in  respect  to  cleanliness.  An 
average  loss  of  0.25  pound  (4  ounces)  of  fat  for  100 
pounds  of  milk  indicates  excellent  work  under  factory 
conditions;  this  means  that  about  93  per  cent  of  the 
fat  in  milk  is  recovered  in  cheese  and  not  over  7  per 
cent  lost  in  whey. 

The  data  embodied  in  the  following  table  include 
the  results  of  several  seasons'  work  in  cheese-fac- 
tories : 

AMOUNT  OF   FAT   IN   WHEY   AT   CHEESE-FACTORIES  DUR- 
ING SEASON 


Month 

Average 
per   cent  of 
fat  in  milk 

Pounds  of  fat  lost  in  whey  from 
100  pounds  of  milk 

3.43 
3.58 
3.64 
3.62 
3.84 
3.98 
4.23 

Lowest 
0.29 
0.20 
0.20 
0.21 
0.22 
0.22 
0.26 

Highest 
0.42 
0.50 
0.36 
0.45 
0.40 
0.46 
0.44 

Average 
0.36 
0.35 
0.28 
0.32 
0.34 
0.37 
0.33 

May  . 

June 

July  
August               

September  
October  

The  tabulated  results  on  the  next  page  show  the 
relative  amounts  of  fat  lost  in  normal  milks  containing 
different  percentages  of  fat.  These  results  are  in 
harmony  with  those  of  other  investigators  and  the 
facts  all  go  to  show  that  the  loss  of  fat  in  cheese- 
making  is  quite  independent  of  the  amount  of  fat  in 
milk.  The  variations  that  occur  in  loss  of  fat  are 
due  either  to  the  defective  condition  of  the  milk  with 
reference  to  bacterial  content,  or  to  some  special  fault 
in  the  details  of  methods  employed  in  cheese-making, 
or  to  botfy  causes. 


MILK    AND    YIELD    OF    CHEESE 


Even  when  cream  is  added  to  normal  milk  to  an 
extent  sufficient  to  raise  the  fat  content  to  7  or  8 
per  cent,  the  increased  loss  of  fat,  though  consider- 
able, is  not  necessarily  greater  in  proportion  to  the 
increase  of  fat 'in  milk. 

AMOUNT   OF   FAT    LOST   IN    CHEESE-MAKING   IN    CASE  OF 
NORMAL    MILKS 


Percent- 

Percent- 

Group 

Number 
of  ex- 
peri- 

Per cent 
of  fat 
in  milk 

Pounds  of  fat  lost  in  whey 
for  100  pounds  of  milk 

age  of  fat 
in  milk 
lost  in 

age  of  fat 
in  milk 
retained 

ments 

whey 

in  cheese 

I 

22 

3.0-3.  S 

Lowest 
0.21 

Highest 
0.39 

Average 
0.32 

9.55 

90.45 

II 

112 

3.5-4.0 

0.21 

0.50 

0.33 

8.33 

91.67 

III 

78 

4.0-4.5 

0.20 

0.46 

0.32 

7.70 

92.30 

IV 

16 

4.5-5.0 

0.17 

0.49 

0.28 

5.90 

94.10 

V 

7 

5.0-5.25 

0.27 

0.35 

0.31 

6.00 

94.00 

Why  it  is  impossible  to  prevent  loss  of  fat  in 
cheese-making. — Attention  has  already  been  called  (p. 
140)  to  the  fact  that  fat  is  present  in  milk  in  the 
form  of  very  small  globules,  one  cubic  centimeter 
of  ordinary  milk  containing  between  one  and  two 
billion  globules.  When  the  rennet-extract  causes 
the  casein  throughout  the  mass  of  milk  to  solidify 
or  coagulate,  the  fat-globules  are  retained  or  im- 
prisoned in  the  solidified  mass  just  where  they 
are  at  the  instant  of  coagulation.  When  the  curd- 
knife  passes  through'  the  solid  mass,  immense  num- 
bers of  the  fat-globules  are  exposed  on  every  cut 
surface  and  billions  of  these  are  disengaged  from 
the  free  surfaces  of  the  small  pieces  of  curd  during 
its  manipulation.  The  fat-globules,  thus  detached 


192     SCIENCE    Ai\D    PRACTICE    OF    CHEESE-MAKING 

from  the  hold  of  the  curd,  float  free  in  the  whey  and 
are  consequently  lost  to  the  cheese. 

Conditions  favoring  loss  of  fat  in  cheese-making. 
—Among  the  numerous  conditions  contributing  to 
an  increased  loss  of  fat  in  cheese-making  are  the  fol- 
lowing : 

(1)  Any    condition    which    interferes    with    com- 
plete   coagulation   of    casein    by    rennet-extract,    such 
as    dilution    with    water,    presence    of    preservatives, 
as  salt,  formalin,  etc.,  necessarily  causes  extra  loss  of 
fat. 

(2)  There  may  occur  cases  of  abnormal  compo- 
sition   of   milk,    in    which    the    casein    is    abnormally 
low   in   relation   to   fat.       Attention   has   already   (p. 
164)   been  called  to  this  condition  as  likely  to  occur 
in  times  of  drouth.       Cheese-makers   do  not  realize 
the  abnormal  nature  of  the  milk  and  so  do  not  ob- 
serve   the    precautions    necessary    in    handling    milk 
that  is  abnormally  high  in   fat  in  relation  to  casein. 
But  another  condition  usually  prevails  at  such  times, 
which  makes  the  losses  of  fat  unavoidable,  and  that  is 
the  presence  of  bacterial  ferments,  resulting  from  the 
accompanying  effects  of  drouth  such  as  contaminated 
water  supply. 

(3)  Failure    to    keep    the    fat    well    distributed 
through    the    milk   before    and    after    adding    rennet 
results   in   some  accumulation   of   fat   at   the   surface 
of  the  milk,  most  of  which  goes  into  the  whey. 

(4)  In  case  of  milk  containing  particles  of  dried 
cream  or  churned   fat-granules,   there   is  usually  in- 
creased loss  of  fat,  unless  the  particles  are  completely 
worked  back  into  the  form  of  emulsion  by  sufficient, 
but  not  rapid,  warming  and  careful  stirring. 


MILK    AND    YIELD    OF    CHEESE  193 

(5)  When  milk  is   run  through  a  separator  and 
the    cream    and    skim-milk    then    remixed,    increased 
loss    of    fat    occurs    when    such    milk    is    made    into 
cheese. 

(6)  Jarring  or  stirring  milk  after  rennet  coagu- 
lation has  commenced  and  before  it  is  completed  may 
cause  serious  loss  of  fat. 

(7)  When  curd  is  cut  in  too  soft  a  condition,  the 
loss  of  fat  is  greater. 

(8)  Added  losses  of  fat  in  whey  are  caused  by 
dull  knives  or  by  violent,  careless  and  rapid  motions 
of  knife  in  cutting  curd. 

(9)  Extra  losses  of  fat  occur  when  the  curd  in  the 
soft  stage  is  roughly  or  carelessly  handled. 

(10)  Another   cause   of   increased   loss   of   fat   in 
whey  is  heating  the  curd  too  rapidly  or  to  too  high  a 
temperature. 

(n)  If  the  curd  is  not  well  firmed  at  the  time 
the  whey  is  removed,  vigorous  hand  stirring  causes 
large  loss  of  fat. 

(12)  Excessive  piling  of  curd,  previous  to  ched- 
daring,  causes  unnecessary  loss  of  fat. 

(13)  If  the  curd  is  salted  at  a  temperature  above 
90°  F.,  fat  is  apt  to  exude  along  with  the  whey  and 
be  lost. 

(14)  If  curd  is  put  in  press  too  warm,  the  amount 
of  fat   lost  in   pressing  increases  on   account  of  the 
greater  softness  of  the  warm  curd. 

(15)  Too    rapid    application    of    pressure    in    the 
cheese-press  increases  loss  of  fat. 

(16)  Fermentations   producing   large   amounts   of 
gas    and    resulting    in    "floating"    curds,  also    curd- 
dissolving    fermentations,    are    attended    with    extra 


194     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

losses  of  fat.  The  conditions  of  cheese-making  have 
to  be  varied  under  such  circumstances  so  as  to  make 
the  best  of  a  bad  matter  and  obtain  as  good  a  product 
as  possible  in  respect  to  texture,  body  and  flavor. 
Such  variations  from  the  usual  conditions  of  cheese- 
making  cause  extra  losses  of  fat  (p.  124). 

(17)  The  making  of  cheese  from  milk  containing 
too  much  acid  results  in  unusual  losses  of  fat,  if  the 
conditions  are  varied  so  as  to  obtain  the  best  product 
possible  from  such  milk  (p.  122). 

(18)  Milling  at  too   high  a  temperature,  or  too 
rapidly,   or  with  dull  knives,  or   feeding  to  mill  too 
fast,   or   allowing  the   curd   to   become   matted   after 
milling, — any  of    these    conditions    increases    loss    of 
fat. 

The  losses  of  casein  in  cheese-making. — The 
larger  portion  of  the  casein  lost  in  cheese-making 
appears  to  be  in  the  form  of  fine  particles  of  the 
coagulated  casein  (paracasein),  which  pass  through 
the  strainer  when  the  whey  is  removed  from  the 
curd.  These  fine  particles  can  readily  be  seen  by 
letting  a  pail  of  freshly  drawn  whey  stand  until  the 
curd  particles  settle.  If  the  whey  is  then  carefully 
'poured  from  the  pail,  a  noticeable  quantity  of  finely 
divided  curd  can  be  seen  at  the  bottom  of  the  pail. 
This  loss  does  not  appear  to  be  entirely  avoidable, 
but  is  needlessly  made  greater  (i)  by  carelessness 
or  violence  in  cutting  curd  and  in  subsequent  han- 
dling when  the  curd  is  still  soft;  (2)  by  agitation 
while  removing  the  whey  from  the  curd;  (3)  by 
imperfect  strainers;  and  (4)  by  any  condition  that 
interferes  with  the  complete  coagulation  of  the 
milk-casein  by  rennet  (p.  24).  The  amount  of 


MILK    AND    YIELD    OF    CHEESE  195 

casein  that  thus  passes  into  the  whey  averages  about 
o.io  pound   for   100  pounds  of   milk. 

In  some  cases  of  badly  contaminated  milk,  casein- 
dissolving  ferments  may  cause  more  or  less  loss  of 
casein. 


FIG.     34 — COMPOSITION     OF     MILK,     SHOWING     PROPORTIONS     OF 
WATER    AND    DIFFERENT    SOLIDS.      THE    NUMBERS   REP- 
RESENT   POUNDS    IN    100  POUNDS     OF     MILK 

COMPOSITION  OF  WHEY 

The  composition  of  whey  (Fig.  35)  varies  ac- 
cording to  (i)  the  composition  of  the  milk  from 
which  it  comes,  and  (2)  the  losses  of  milk  constit- 
uents due  to  conditions  attending  the  operations 
of  cheese-making.  It  is  obvious  that  the  larger  the 
percentage  of  sugar,  albumin  and  soluble  salts  in 


196     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

milk,  the  larger  will  be  their  amount  in  whey.  The 
matter  of  losses  of  fat  and  casein  we  have  already 
treated.  The  amount  of  acid  in  whey  varies 
greatly,  depending  largely  on  the  time  when  the 
determination  of  acidity  is  made.  When  the  whey 
is  removed  from  the  curd,  the  acidity  (equivalent 


FIG.  35 — DISTRIBUTION  OF  MILK  CONSTITUENTS  IN 
CHEESE  AND   WHEY 

From  100  pounds  of  milk,  we  obtain  '10.6  pounds  of  cheese  and  89.4  pounds  of 
whey.  The  cheese  contains  3.9  pounds  of  water,  3.7  fat,  2.4  casein,  Q.f  salts  and 
albumin  and  0.2  sugar.  The  whey  contains  83.1  pounds  of  water,  5.25  sugar  and 
•alts,  0.28  fat,  0.10  casein  and  0.67  albumin.  The  lower  part  of  the  diagram  shows 
amount  and  composition  of  cheese.  The  remainder  is  whey  (water  and  whey- 
solids.) 

to  lactic  acid)  varies  from  0.16  to  0.18  per  cent,  and 
this  amount  increases  to  the  end  of  the  cheese- 
making  process.  The  whey,  when  it  first  separates 
from  the  curd,  shows  less  acidity  than  the  milk 
from  which  it  comes,  because  the  whey  does  not 


MILK   AND    YIELD    OF    CHEESE 


197 


contain  the  milk-casein,  which,  as  we  have  seen 
(p.  145),  has  the  power  of  neutralizing  considerable 
alkali,  and  of  acting  in  this  way  like  an  acid.  The 
percentage  of  sugar  in  whey  depends  upon  the  time 
when  the  whey  is  tested,  the  sugar  decreasing  in 
amount  as  it  is  changed  into  lactic  acid. 

In  closing  this  discussion  of  the  losses  of  milk 
constituents  in  cheese-making,  we  give  below  tab- 
ulated results  of  work  showing  the  composition  of 
whey  as  obtained  at  cheese-factories  in  New  York 
through  the  work  of  the  New  York  experiment 
station. 

COMPOSITION   OF  CHEESE-FACTORY   WHEY 


Month 

Per  cent 
of  water 

Per  cent 
of  solids 

Per  cent 

of  fat 

Per  cent 
of  proteins 
(chiefly 
albumin) 

Per  cent 
of  sugar, 
salts,  etc. 

April 

93  17 

6  83 

0  40 

0  73 

5  70 

May  
June  
July  

92.98 
92.99 
93.05 

7.02 
7.01 
6.95 

0.38 
0.31 
0.35 

0.81 
0.88 
0.83 

5.83 
5.82 
5.77 

August  
September  
October  

93.08 
93.18 
93.04 

6.92 
6.82 
6.96 

0.38 
0.41 
0.38 

0.80 
0.85 
0.98 

5.74 
5.56 
5.60 

Average  

93.04 

6.96 

0.36 

0.84 

5.76 

The  following  figures  show  the  extreme  variations 
in  the  constituents  of  whey  during  the  period  of 
investigation : 


Lowest 
per  cent 

Highest 
per  cent 

Solids 

6.43 

7.52 

Fat 

0  22 

0  55 

Proteins  
Sugar  salts  etc                     .                 ...        .... 

0.65 
5.39 

1.07 
6.43 

198     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

THE  RELATION  OF  WATER  TO  YIELD  OF 
CHEESE 

As  we  have  seen,  the  amount  of  solids  in  cheese 
is  determined  by  the  amount  of  fat  and  casein  in 
milk  when  the  conditions  of  manufacture  are  nor- 
mal. When  we  come  to  consider  the  amount  of 
water  held  in  cheese,  we  find  that  it  bears  no  rela- 
tion whatever  to  the  amount  of  water  in  milk,  but 
that  it  is  dependent  upon  the  conditions  present  in 
the  operations  of  cheese-making,  such  as  the  degree 
of  fineness  or  coarseness  in  cutting  curd,  temper- 
ature used  in  heating  curd,  degree  of  acidity, 
amount  of  salt,  etc.  (p.  45).  The  amount  of  water 
in  cheese  can  easily  be  made  to  vary  10  per  cent. 
Fresh  cheese  contains  an  average  of  37  per  cent  of 
water,  but  in  actual  factory  work  the  variations  may 
be  very  wide,  especially  where  cheese  is  manufac- 
tured for  export  trade  at  one  part  of  the  season  and 
for  home  trade  at  another.  Therefore,  when  we  are 
discussing  yields  of  cheese  from  milk,  and  especially 
in  the  case  of  comparison  of  different  milks,  it  is 
absolutely  necessary  to  know  the  percentage  of 
water  in  the  cheese.  When  we  compare  yields 
of  cheese  from  different  milks  or  under  different  con- 
ditions of  manufacture,  we  should  base  our  com- 
parison on  the  yield  of  cheese  which  contains  a 
uniform  percentage  of  moisture,  if  the  results  are 
to  have  any  definite  relation  to  the  milk  con- 
stituents. 

So  important  is  it  for  us  to  appreciate  the  extent 
of  variation  of  water  in  cheese,  as  made  at  cheese- 
factories,  that  we  will  present  data  obtained  by  the 
New  York  experiment  station  in  200  experiments 


MILK    AND    YIELD    OF    CHEESE 


199 


carried  on  at  cheese-factories  under  the  usual  con- 
ditions. In  the  table  below,  we  present  the  results 
in  groups,  based  on  the  percentage  of  fat  in  milk; 
in  each  group  we  give  (i)  the  extreme  variations  in 
yield  of  cheese;  (2)  the  percentage  of  moisture 
in  the  cheese;  and  (3)  the  corresponding  yield  of 
cheese  based  on  a  content  of  37  per  cent  of  water. 


YIELD  OF  CHEESE  AS  AFFECTED  BY  MOISTURE 


Pounds  of  cheese 

Number 

Per  cent 

Pounds  of  cheese 

Per  cent 

(containing  37  per 

of  experi- 

of fat 

made  for  100 

of  water 

cent  of  water) 

ments 

in  milk 

pounds  of  milk 

in  cheese 

made  for  100 
pounds  of  milk 

22 

3.00-3.49 

Lowest  -  8.47 

Highest-  9.68 

34.77 
39.09 

, 

8.43 
9.46 

59 

3.50-3.74 

Lowest  -  9.25 
Highest-10.42 

33.75 
40.47 

9.32 
10.60 

51 

3.75-3.99 

Lowest  -  9.60 
Highest-  11.  00 

32.69 
40.17 

9.76 
10.76 

43 

4.00-4.19 

Lowest  -10.24 
Highest-  12.  44 

34.15 
42.90 

10.38 
10.93 

25 

4.20-4.40 

Lowest  -10.64 
Highest-13.17 

33.53 
43.89 

11.03 
12.03 

In  studying  these  results,  we  see  that  in  the  case 
of  each  group  the  cheese  yield  varies  widely,  as 
shown  in  the  third  column  of  the  table;  and  also 
that  the  percentage  of  water  varies  widely,  as 
shown  in  the  fourth  column.  To  illustrate,  we 
will  take  the  group  representing  milk  containing 
4  to  4.19  per  cent  of  fat.  The  factory  yield  of 
cheese  in  this  group  varies  from  10.24  to  12.44 
pounds,  a  difference  of  2  pounds,  while  the  water 
in  loo  pounds  of  cheese  varies  from  34.15  to  42.90 
pounds.  In  the  last  column  we  see  what  the  nor- 
mal variation  should  be  in  the  yield  of  cheese 


2OO     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

having  the  same  percentage  (37)  of  water;  it  goes 
from  10.38  to  10.93,  a  variation  of  0.55  pound,  as 
against  an  actual  variation  of  2  pounds.  This 
difference,  1.45  pounds,  is  wholly  due  to  differ- 
ence of  water  in  cheese.  In  the  last  group  of 
the  table,  the  factory  yield  of  cheese  varies  2.53 
pounds,  while  the  normal  variation  would  be  only 
i.o  pound.  We  see  at  the  same  time  that  the  amount 
of  water  in  100  pounds  of  cheese  varies  over  10 
pounds. 

These  results  might  appear  to  indicate  that 
cheese-makers  have  no  control  over  the  amount  of 
water  in  cheese,  but  such  a  conclusion  would  not 
be  justified,  because  it  is  well  known  that  a  skill- 
ful cheese-maker,  under  normal  conditions,  can 
control  the  amount  of  water  in  cheese  within  3 
or  4  per  cent,  so  that  the  normal  range  of  varia- 
tion is  usually  between  35  and  38  per  cent.  The  large 
amounts  of  water  in  the  cases  noted  in  the  preceding 
table  appeared  there,  not  because  the  cheese-makers 
had  no  control  of  the  process,  but  for  the  very  opposite 
reason,  that  they  did  have  such  control  and  deliber- 
ately made  the  cheese  to  hold  a  high  percentage  of 
water 

THE    COMPARATIVE   VALUE   OF   DIFFER- 
ENT   MILKS    IN    RELATION    TO 
CHEESE-PRODUCING     SOLIDS 

From  what  has  preceded,  it  can  be  readily  un- 
derstood that  we  can  divide  the  constituents  of  milk 
into  two  general  classes,  when  considered  with  ref- 
erence to  their  relations  to  cheese.  The  , casein,  fat 


MILK   AND    YIELD    OF    CHEESE  2OI 

and  insoluble  salts  constitute  one  group,  furnishing 
most  of  the  solid  matter  in  cheese,  and  we  can  call 
these  constituents  cheese-producing  solids.  On  an 
average,  milk  contains  about  0.90  per  cent  of  salts, 
of  which  about  0.25  pound  goes  into  cheese  for  each 
too  pounds  of  milk  and  0.65  pound  into  whey,  vary- 
ing, of  course,  with  many  conditions.  The  other 
constituents  of  the  milk-solids,,  the  sugar,  the  albu- 
min and  the  soluble  salts,  those  constituents  of  the 
milk  that  exist  in  true  solution,  pass  largely  into 
the  whey  and  are  lost,  except  in  so  far  as  they  are 
held  by  the  water  or  whey  in  the  cheese.  Their 
amount  in  cheese  will  depend  upon  the  amount  of 
whey  retained  in  the  cheese.  Those  solid  constitu- 
ents existing  in  solution  in  the  whey  we  may  prop- 
erly characterize  as  whey-solids.  This  division  of  milk 
constituents  into  cheese-producing  solids  and  whey- 
solids  is,  of  course,  not  strictly  accurate,  because 
small  amounts  of  cheese-solids  pass  into  whey  and 
small  amounts  of  whey-solids  are  retained  in 
cheese.  But,  for  the  purpose  of  studying  the  gen- 
eral relations  of  milk-solids  to  cheese,  the  classifi- 
cation is  close  enough.  The  figures  presented  be- 
low are  largely  taken  from  work  done  at  the  New 
York  experiment  station,  covering  a  period  of  four 
years  and  are  largely  derived  from  actual  cheese- 
factory  conditions. 

The  cheese-producing  solids  were  found  to  aver- 
age 6.50  pounds,  varying  in  extreme  cases  from 
5.25  to  7.75  pounds  for  100  pounds  of  milk,  but  the 
greater  portion  of  factory  milk  comes  within  the 
narrower  limits  of  5.75  to  7.25  pounds.  The  whey- 
solids  of  milk  varied  from  5.75  to  6.75  pounds  and 


2O2     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


averaged  6.25  pounds.  Stated  in  another  form,  49 
per  cent  of  the  milk-solids  goes  into  whey  and  5.1  per 
cent  into  cheese  as  an  average  of  factory  milk. 

The  following  arrangement  shows  the  extent  of 
average  monthly  variation  during  the  factory 
season : 

CHEESE-PRODUCING      SOLIDS      AND      WHEY      SOLIDS      IN 
CHEESE-FACTORY    MILK 


Month 

Percentage  of  cheese- 
producing  solids  in  milk 

Percentage  of  whey- 
solids  in  milk 

Lowest 

Highest 

Average 

Lowest 

Highest 

Average 

April... 

5.75 
5.68 
6.06 
6.01 
6.09 
6.27 
7.02 

6.14 
6.91 
6.61 
6.60 
6.76 
7.14 
7.69 

5.97 
6.17 
6.36 
6.30 
6.48 
6.78 
7.29 

5.94 
6.11 
6.17 
6.10 
6.06 
5.86 
5.96 

6.09 
7.78 
6.44 
6.47 
6.35 
6.26 
6.44 

6.01 
6.26 
6.28 
6.22 
6.17 
6.08 
6.21 

May  
June  

July       

August  
September.  .  . 
October  

Expressing  the  relations  of  the  general  averages 
in  the  preceding  table  in  the  form  of  percentages  of 
milk-solids,  we  have  the  following  table: 


Month 

Pounds  of  milk- 
solids  in  100 
pounds  of  milk 

Percentage  of  total 
solids  of  milk  in 
form  of  cheese- 
producing  solids 

Percentage  ot  total 
solids  in  milk  in 
form  of  whey- 
solids 

April... 

11.98 

49.8 

50  2 

May.. 

12.43 

49  6 

50  4 

June  
July  
August  
September  . 
October  

12.64 
12.52 
12.65 
12.86 
13.50 

50.3 
50.3 
51.2 
52.7 
54.0 

49.7 
49.7 
48.8 
47.3 
46.0 

We  see  a  general  tendency  for  the  cheese-producing 
solids  in  milk  to  increase  during  the  factory  season, 


MILK   AND    YIELD    OF    CHEESE 


203 


which  is  only  another  way  of  saying  that  the  per- 
centage of  fat  and  of  casein  increases  with  advance 
of  lactation,  (p.  166). 

Before  leaving 'this  phase  of  the  subject,  it  will 
be  found  interesting  to  compare  the  ratio  of  cheese- 
producing  solids  and  whey-solids  in  rnilk  varying 
considerably  in  percentage  of  fat.  From  the  figures 
in  the  following  table,  it  is  very  strikingly  shown 
that  in  normal  milk  rich  in  fat  a  very  much  larger 
proportion  of  the  milk-solids  goes  into  cheese  and 
correspondingly  less  into  whey,  than  in  the  case  of 
milk  poorer  in  fat. 

CHEESE-PRODUCING      SOLIDS      AND      WHEY      SOLIDS      IN 
RICH   AND  POOR   MILK 


Per  cent 

Per  cent 

Per  cent  of 

Per  cent  of 

Per  cent 

Per  cent 

of  cheese- 

of  whey- 

solids  in  form 

solids  in  form 

of  solids 

of  fat 

producing 

solids 

of  cheese- 

of  whey- 

solids 

solids 

solids 

11.80 

3.26 

5.71 

6.09 

48.4 

51.6 

12.65 

3.76 

6.89 

5.76 

54.5 

45.5 

12.75 

4.01 

6.47 

6.28 

50.7 

49.3 

14.30 

4.28 

7.32 

6.98 

51.1 

48.9 

14.50 

4.89 

8.24 

6.26 

56.9 

43.1 

14.90 

5.38 

8.54 

6.36 

57.3 

42.7 

15.40 

5.78 

9.06 

6.34 

58.8 

41.2 

DISTRIBUTION   OF   MILK   CONSTITUENTS 
IN  WHEY  AND  CHEESE 

Having  learned  what  the  principal  losses  of 
cheese-producing  solids  are,  we  will  next  show  by 
illustrations  in  what  amounts  the  different  constit- 
uents of  milk  are  divided  between  whey  and 
cheese  in  cheese-making.  The  following  results 
are  based  on  average  losses  of  milk  constituents. 


2O4     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


The  cheese  is  assumed  to  contain  37  per  cent  of 
water,  about  5  per  cent  of  salts  and  no  allowance 
is  made  for  mechanical  losses  other  than  as  indi- 
cated 


Water 

Milk- 
solids 

Fat 

Casein 

Albumin 

Sugar, 
ash,  etc. 

I. 

Milk... 
Whey.. 
Cheese 

Pounds 
100.00 
91.70 
8.30 

Pounds 
88.60 
85.55 
3.05 

Pounds 
11.40 
6.15 
5.25 

Pounds 
3.00 
0.21 
2.79 

Pounds 
2.10 
0.10 
2.00 

Pounds 
0.60 
0.57 
0.03 

Pounds 
5.70 
5.27 
0.43 

II. 

Milk... 
Whey.. 
Cheese 

100.00 
89.40 
10.60 

87.00 
83.10 
3.90 

13.00 
6.30 
6.70_ 

4.00 

0.28 
3.72 

2.50 
0.10 
2.40 

0.70 
0.67 
0.03 

5.80 
5.25 
0.55 

III. 

Milk... 
Whey.. 
Cheese 

100.00 
87.10 
12.90 

85.50 
80.75 
4.75 

14.50 
6.35 
8.15 

5.00 
0.35 
4.65 

2.90 
0.10 
2.80 

0.75 
0.72 
0.03 

5.85 
5.18 
0.67 

In  connection  with  this  table,  study  Figs.  34,  35 
and  36. 

RELATION  OF  MILK-FAT  TO   CHEESE 
YIELD 

Much  study  has  been  given,  especially  in  New 
York,  to  the  quantitative  relations  existing  between 
the  percentage  of  fat  in  milk  and  the  yield  of  cheese, 
or  the  amount  of  cheese  corresponding  to  one  pound 
of  fat  in  milk.  The  relation  is  a  very  simple  one  to 
calculate  and  is  found  by  dividing  the  number  of 
pounds  of  cheese  made  from  TOO  pounds  of  milk  by 
the  number  representing  the  per  cent  of  fat  in  milk. 
For  example,  the  yield  of  cheese  from  100  pounds 
of  milk  containing  3  per  cent  of  fat  is  8.31  pounds; 


MILK    AND    YIELD    OF    CHEESE  2C>5 

the  ratio  of  milk-fat  to  cheese  yield  is,  therefore, 
8.31-^3,  which  equals  2.77;  that  is,  in  this  case,  one 
pound  of  fat  in  milk  is  equivalent  to  2.77  pounds  of 
cheese.  In  the  case  of  milk  containing  4  per  cent  of 
fat  and  producing  10.60  pounds  of  cheese  for  100 
pounds  of  milk,  each  pound  of  fat  in  milk  is  equiva- 
lent to  2.65  pounds  of  cheese. 

The  study  of  this  relation  was  first  undertaken  at 
the  New  York  experiment  station  to  ascertain 
whether  a  pound  of  fat  in  all  normal  milks  is 
equivalent  to  the  same  amount  of  cheese.  The 
bearing  of  this  point  upon  the  use  of  fat  in  milk  as 
a  basis  of  paying  for  milk  at  cheese-factories  is 
obvious.  If  a  pound  of  fat  in  milk  were  always 
equivalent  to  the  same  amount  of  cheese,  then  no 
question  could  arise  as  to  the  strict  accuracy  of  a 
milk-fat  basis  in  making  dividends.  If  the  amount 
of  cheese  made  for  a  pound  of  fat  in  milk  varies, 
then  the  fat  could  not  be  regarded  as  a  strictly  ac- 
curate measure  of  cheese  yield,  and  other  points  than 
yield  would  need  to  be  considered,  such  as  the  quality 
of  the  cheese,  in  measuring  the  value  of  milk  for 
cheese-making.  The  details  of  the  subject  of  methods 
of  paying  for  milk  at  cheese-factories  will  be  con- 
sidered later  (p.  253). 

We  have  already  seen  that  the  yield  of  cheese 
is  chiefly  dependent  upon  two  constituents  of  milk, 
casein  as  well  as  fat.  It  is  obvious  that  if  fat  and 
casein  were  always  present  in  milk  in  the  same 
relative  proportions,  then  the  yield  of  cheese  would 
always  be  in  the  same  uniform  ratio  to  milk-fat. 
But  we  have  found  (p.  164)  that  the  ratio  of  fat 
and  casein  in  milk  varies  considerably  and,  for 


2OO     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

this  reason,  the  ratio  of  milk-fat  to  yield  of  cheese 
must  also  vary.  It  is  a  matter  of  practical  interest 
and  importance  to  know  what  the  extent  of  such 
variations  may  be. 


FIG.    36 — YIELD     AND     CONSTITUENTS     OF     CHEESE     FROM     100 
POUNDS     OF    MILK    CONTAINING     AMOUNTS     OF    FAT 
VARYING  FROM  0.10  PER  CENT    (SEPARATOR  SKIM- 
MILK)    UP   TO  6.00  PER  CENT. 

The  figures  Immediately  above  each  column  .erlve  the  number  of  pounds  of 
Cheese  (containing  37  per  cent  of  water)  made  from  100  pounds  of  milk.  The 
figures  within  the  diagram  give  the  pounds  of  each  constituent  in  the  cheese. 
The  figures  at  the  extreme  top  of  the  diagram  indicate  percentages  of  fat  in 
milk. 

Taking  milk  as  it  averages,  we  find  the  following 
variation  of  relation  between  fat  and  cheese  yield  in 
normal  milks  containing  different  amounts  of  fat. 
The  cheese  yield  is  based  on  a  uniform  percentage 
of  water  in  the  cheese,  37  per  cent. 


MILK   AND    YIELD   OF    CHEESE 


207 


RATIO  OF  FAT  TO  CHEESE  YIELD  IN   NORMAL   MILK 


Per  cent  of 
fat  in  milk 

Per  cent  of 
casein  in  milk 

Pounds  of  cheese 
made  from  100 
pounds  of  milk 

Pounds  of  cheese 
made  for  each 
pound  of  fat 
in  milk 

3.00 

2.10 

8.30 

2.77 

3.25 

2.20 

8.88 

2.73 

3.50 

2.30 

9.45 

2.70 

3.75 

2.40 

10.03 

2.67 

4.00 

2.50 

10.60 

2.65 

4.25 

2.60 

11.17 

2.63 

4.50 

2.70 

11.74 

2.61 

4.75 

2.80 

12.31 

2.59 

5.00 

2.90 

12.90 

2.58 

In  our  study  of  the  ratio  of  fat  and  casein  in 
milk  (p.  164),  it  was  seen  that  the  casein  does  not 
increase  as  rapidly  as  fat  does,  and  that,  therefore, 
milk  richer  in  fat  usually  contains  less  casein  in 
proportion  to  fat  than  does  milk  less  rich  in  fat. 
In  harmony  with  this  condition,  and  as  a  result  of 
it,  the  amount  of  cheese  made  for  a  pound  of  milk- 
fat  decreases  as  the  percentage  of  fat  in  milk 
increases.  This  is  clearly  shown  in  the  preceding 
table. 

An  interesting  fact  shown  in  this  table  is  that 
the  rate  of  decrease  of  the  ratio  of  fat  to  cheese 
yield  is  less  rapid  as  the  percentage  of  fat  in  milk 
increases.  Thus,  in  the  case  of  milks  containing 
3  and  3.25  per  cent  of  fat,  the  decrease  of  cheese 
yield  in  relation  to  fat  is  from  2.77  to  2.73,  a  differ- 
ence of  0.04  pound ;  between  3.25  and  3.50,  and  also 
between  3.50  and  3.75,  the  decrease  is  0.03;  for 
each  0.25  per  cent  of  increase  of  milk-fat  from 
3.75  to  4.75  per  cent,  the  decrease  in  the  ratio  is 
only  0.02;  and  between  4.75  and  5.00  per  cent, 
the  decrease  is  only  o.oi.  This  is  explained  by  the 


2O8     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

fact,  already  emphasized  (p.  190),  that  in  the  case 
of  milk  rich  in  fat,  a  smaller  proportion  of  the  fat 
is  lost  in  cheese-making  than  in  the  case  of  milk 
poorer  in  fat. 


PER  CENT.  OF  FAT  IN  MILK  AND  YIELD  OF  CHEESE 


FIG.     37 — DIAGRAM     SHOWING     YIELD     AND     CONSTITUENTS     OF 

CHEESE    FROM    100   POUNDS   OF  MILK  OF  DIFFERENT  BREEDS 

OF    DAIRY    COWS 

The  figures  immediately  above  each  column  give  the  number  of  pounds 
of  cheese  (containing  37  per  cent  of  water)  made  from  100  pounds  of  milk.  The 
figures  in  the  diagram  give  the  pounds  of  each  constituent  in  the  cheese.  The 
figures  at  the  top  of  the  diagram  indicate  percentage  of  fat  in  milk. 

•In  this  connection,  it  will  be  interesting  to  observe 
how  the  matter  works  out  when  applied  in  the  case 
of  the  milk  of  different  breeds  of  cows. 


MILK    AND    YIELD    OF    CHEESE 


209 


RATIO  OF  FAT  TO  CHEESE  YIELD  IN   MILK  OF  DIFFERENT 
BREEDS 


Pounds  of 

Pounds  of 

Per  cent 

Per  cent 

cheese  made 

cheese  made 

Breed 

of  fat 

of  casein 

for   100 

for  each 

in  milk 

in  milk 

pounds 

pound  of  fat 

of  milk 

in  milk 

3  26 

2  20 

8  90 

2  73 

Ayrshire               

3.76 

2.46 

10.14 

2.70 

American  Holderness..  . 

4.01 

2.63 

10.82 

2.70 

4  28 

2  79 

11  52 

2  70 

Devon     

4.89 

3.10 

13.02 

2.66 

Guernsey       

5  38 

2.91 

13.51 

2.51 

5  78 

3  03 

14  36 

2  49 

Before  closing"  our  discussion  of  this  subject,  we 
wish  to  call  attention  to  the  fallacy  that  may  be 
introduced  by  wide  variations  in  the  water  content 
of  cheese,  when  we  are  making  a  comparison  of  the 
yield  of  cheese  with  reference  to  the  milk-fat.  For 
example,  100  pounds  of  milk  containing  4  per  cent 
of  fat  may  be  made  into  cheese  with  a  yield  of  10.40 
pounds  in  one  case,  and  n.oo  pounds  in  another, 
the  difference  being  due  wholly  to  water.  In  one 
case  the  yield  is  2.60  pounds  for  one  pound  of  milk- 
fat;  in  the  other,  it  is  2.75  pounds.  It  is  thus  seen 
that,  when  such  comparisons  are  to  be  made  with 
reference  to  the  relation  of  fat  to  yield  of  cheese, 
the  cheese  should  contain  the  same  percentage  of 
water.  The  table  on  page  199  well  illustrates  the 
variations  of  yield  in  relation  to  water.  If  we  use 
the  results  there  given  as  a  basis  for  calculating 
the  yield  of  cheese  in  relation  to  milk-fat,  we  find 
that  the  amount  of  cheese  made  for  one  pound  of 
milk-fat  varies  from  2.51  to  3.11,  when  we  take  the 
factory  yield,  with  its  great  variation  of  water;  but, 


21O      SCIENCE   AND    PRACTICE    OF    CHEESE-MAKING 

if  the  calculation  is  based  on  cheese  containing  a  fixed 
percentage  of  water,  the  cheese  yield  varies  in  relation 
to  fat  only  from  2.61  to  2.89.  This  is  a  much  nar- 
rower range  and  represents  such  variations  as  are 
properly  due  to  differences  in  composition  of  milk. 


CHAPTER  XVIII 
Methods  of  Calculating  Yield  of  Cheese 

In  the  chapter  preceding,  we  have  seen  that  fat 
and  casein  in  milk  furnish  most  of  the  solid  mate- 
rial which  we  find  in  cheese;  we  have  also  seen  that 
certain  amounts  of  fat  and  of  casein  are  inevitably 
lost  in  whey  during"  the  operations  of  cheese-mak- 
ing; and  we  have  further  seen  that  the  amount  of 
water  in  cheese  may  be  made  to  vary  largely  or 
may  be  held  within  comparatively  narrow  limits, 
being  controlled  by  the  conditions  used  in  the 
process  of  cheese-making.  From  our  preceding 
discussion,  it  might  seem  that  the  relations  between 
composition  of  cheese  and  yield  of  milk  were  suf- 
ficiently understood  to  enable  us  to  calculate  the 
amount  of  cheese  yield  when  the  percentages  of  fat 
and  of  casein  in  milk  are  known,  or  even  when  the 
fat  alone  is  given.  As  a  matter  of  fact,  several 
different  methods  have  been  proposed  and  have 
been  employed  in  studying  problems  of  cheese 
yield.  There  is  an  advantage  in  having  some  fairly 
reliable  method  for  ascertaining  the  amount  of 
cheese  that  can  be  made  from  100  pounds  of  milk. 
Results  thus  obtained  afford  a  basis  of  comparison 
with  actual  results.  A  cheese-maker  can,  by  such 
means,  ascertain  if  his  losses  in  cheese-making  are 
excessive  or  if  he  is  retaining  too  much  or  too  little 
water  in  cheese. 

811 


212     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

The  different  methods  of  calculating  cheese  yield 
which  have  been  in  use  have  never  been  carefully 
compared  in  such  a  way  as  to  show  their  relative 
accuracy  or  value.  It  has  seemed  desirable  that  such 
a  study  should  be  made,  and  it  is  now  our  purpose 
to  take  up  for  consideration  the  various  methods 
referred  to.  We  shall  discuss,  in  the  case  of  each 
method,  their  underlying-  principles,  indicate  the 
points  of  fundamental  weakness,  and  give  the  results 
of  an  exhaustive  comparative  study,  based  upon  an 
application  of  each  method  to  200  experiments  in 
cheese-making,  using  for  this  purpose  the  work  done 
at  the  New  York  experiment  station,  which  appears 
to  offer  the  only  material  sufficiently  complete  to  be 
available  for  such  an  investigation. 

The  methods  which  have  been  proposed  for  use 
in  calculating  the  amount  of  green  cheese  are  the 
following : 

(1)  The   use   of   the   percentage   of   fat   in   milk, 
which,  expressed  as  a  formula,  is: 

Yield  of  cheese=2.7  Fat.  , 

(2)  The  use  of  the  percentage  of  fat  in  milk  and, 
in  addition,  a  constant  factor.     This,  expressed  as  a 
formula,  is: 

Yield  of  cheese=i.i  Fat+5-9. 

(3)  The    use    of    the    percentage    of    fat    and    of 
casein,    which    can    be    expressed    in    the    following 
form : 

Yield  of  cheese=i.i  Fat-f-2.5  Casein. 

(4)  The  use  of  the  percentage  of  fat  in  milk  and 
of  the   solids-not-fat.     This   is   somewhat  more  com- 
plicated and  is  expressed  thus: 

Yield  of  cheese=(Solids3not-fat  +  0.91  Fat)  x   1.58 


CALCULATING   YIELD   OF   CHEESE  213 

(5)  A  new  method  based  on  the  use  of  the  per- 
centage of  fat  and  the  percentage  of  casein   (either 
actual  or  calculated).     The  general  formula   for  this 
method  is  as  follows: 

Yield  of  chcc=o=(Fat  "  °-°7  Fat  +  Casein  ~  °-10)  x  l-09 

1.00  —  Water  in  cheese  (expressed  as  hundredths) 

As  will  be  pointed  out  later,  this  can  be  much 
simplified,  becoming 

Yield  of  cheese=(Fat-f  Casein)Xi-63 
in  the  case  of  cheese  containing  a  uniform  amount  of 
water  (37  per  cent).  When  only  the  fat  is  known  and 
the  casein  is  calculated  from  the  formula  on  p.  170 
the  formula  for  both  casein  calculation  and  calcu- 
lation of  cheese  yield  is  simplified  into  one: 

(6)  Yield  of  cheese=2.3  Fat  +1.4. 

These  last  formulas,  based  upon  results  of  New 
York  experiment  station  work,  are  now  published  for 
the  first  time. 

Before  giving  the  detailed  results  of  our  com- 
parative study  of  these  different  methods,  we  will 
discuss  each  one  separately,  explaining  underlying 
principles  and  thus  learning  how  the  methods  came 
to  be  suggested. 

METHOD  BASED  ON  RELATION  OF  FAT  TO 
YIELD  OF  CHEESE      (i) 

The  basis  of  this  method  has  been  discussed  in 
the  chapter  preceding.  In  the  investigations  carried 
on  at  the  New  York  experiment  station,  covering 
all  varieties  of  factory  conditions,  it  was  found  that 
when  the  yield  of  cheese  for  100  pounds  of  milk  was 
divided  by  the  number  representing  the  percentage 
of  fat  in  milk,  the  averages,  season  by  season,  and 


214     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

factory  by  factory,  were  very  uniform,  being  very 
close  to  2.72  pounds  of  cheese  for  one  pound  of  fat 
in  milk.  The  individual  results  giving  the  average 
varied  widely,  from  2.51  to  3.11.  These  extreme 
variations  were  due  to  wide  variations  in  the  water 
content  of  the  cheese  rather  than  to  variation  in 
the  real  relation  of  fat  to  cheese  yield  proper,  as 
we  have  pointed  out  in  the  chapter  preceding.  Based 
on  a  uniform  percentage  of  water  in  cheese,  the  va- 
riations would  be  within  much  less  wide  limits, 
ranging  from  2.61  to  2.89.  This  variation  was  due 
mainly  to  variation  in  the  relation  of  the  fat  and 
casein  in  the  milk  and,  in  some  cases,  to  excessive 
losses  experienced  in  the  process  of  cheese-making. 
The  average  result  (2.7)  is  based  upon  milk  con- 
taining 3.75  per  cent  of  fat,  2.46  per  cent  of  casein 
and  upon  cheese  containing  nearly  37  per  cent  of 
water.  The  ratio  of  milk-fat  to  casein  is,  therefore, 
I  ;o.665.  When  the  ratio  of  fat  and  casein  varies 
widely  from  this,  we  shall  get  more  or  less  cheese 
than  that  called  for  by  the  rule.  Thus,  in  milk  in 
which  the  casein  is  high  in  relation  to  fat,  as  often 
happens  in  milk  low  in  fat,  the  formula  gives  too 
low  results  (p.  207)  ;  while  the  reverse  is  true  in 
case  of  milk  high  in  fat  in  relation  to  casein,  as 
often  happens  in  milk  rich  in  fat  (p.  209).  There- 
fore, as  a  result  of  the  variations  of  the  relation  of 
fat  and  casein  in  cheese-factory  milks,  we  may  ex- 
pect this  method  to  give  results  varying  from  the 
actual  yield  of  cheese,  in  extreme  and  uncommon 
cases,  to  an  extent  equal  to  0.5  to  0.75  pound  of 
cheese  for  100  pounds  of  milk.  When  the  variation 
is  greater  than  this,  it  is  usually  due  to  excessive  or 
deficient  amounts  of  water  in  cheese. 


CALCULATING    YIELD   OF    CHEESE  215 

METHOD  BASED  ON  FAT  IN  MILK  AND  A 
FIXED  NUMBER  ADDED     (2) 

This  method,  stated  in  the  form  of  a  rule,  is  as 
follows:  Multiply  the  number  representing  the 
per  cent  of  fat  in  milk  by  i.i  and  to  the  result  add 
5.9.  This  formula  was  worked  out  at  the  Wiscon- 
sin experiment  station  and  is  based  upon  certain 
facts  which  will  be  briefly  considered.  One  pound 
of  milk- fat  in  butter  can  readily  hold  about  0.18 
pound  of  water  and  it  can  just  as  readily  hold  the 
same  amount  in  cheese.  We  multiply  the  per  cent 
of  fat  in  milk  by  i.i  instead  of  1.18,  because  not  all 
of  the  milk-fat  goes  into  the  cheese.  To  illustrate, 
take  milk  containing  4  per  cent  of  fat;  in  cheese- 
making,  about  3.72  pounds  of  this  fat  in  100  pounds 
of  milk  goes  into  cheese.  This  figure,  multiplied 
by  1. 1 8,  equals  nearly  4.40,  the  same  as  4  multiplied 
by  i.i.  In  other  words,  the  amount  of  fat  that 
actually  goes  into  cheese  multiplied  by  1.18  gives 
about  the  same  result  as  the  amount  (per  cent)  of 
fat  in  milk  multiplied  by  1. 1. 

The  next  question  that  presents  itself  is  as  to 
why  we  add  the  particular  number  5.9  to  the  fat 
multiplied  by  i.i.  This  figure  is  based  upon  the 
amount  of  cheese  that  can  be  made  from  100  pounds 
of  separator  skim-milk  of  average  composition,  and 
is  supposed  to  account  for  the  milk-casein,  the  in- 
soluble salts  and  the  moisture  not  provided  foi  in 
the  milk-fat.  It  is  in  reality  taking  account  of 
casein  in  milk,  but  only  of  the  same  amount  for  all 
milks. 

The  inherent  weak  points  of  this  method  are  the 
following:  (i)  In  the  case  of  excessive  losses  of 


2l6     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

fat  in  cheese-making,  the  result  found  by  multi- 
plying milk- fat  by  i.i  is  too  high.  (2)  The  estimate 
of  5.9  pounds  as  the  measure  of  the  cheese-making 
value  of  casein  in  skim-milk  is  based  upon  skim- 
milk  of  average  composition.  Therefore,  in  milk 
low  in  percentage  of  casein,  5.9  is  too  high,  while 
in  milk  high  in  casein,  the  figure  is  too  low.  The 
method  is  faulty  in  that  its  accuracy  depends  upon 
a  uniform  percentage  of  casein  in  all  milks,  and  we 
know  that  there  are  quite  wide  variations. 

METHOD  BASED  ON  FAT  AND  CASEIN  IN 
MILK     (3) 

This  method  of  finding  the  yield  of  cheese,  stated 
in  the  form  of  a  rule,  is  as  follows:  Multiply  the 
number  representing  the  per  cent  of  fat  in  milk 
by  i.i,  and  to  this  add  the  result  obtained  in  multi- 
plying by  2.5  the  number  representing  the  per  cent 
of  casein  in  milk.  This  formula  was  originally 
worked  out  at  the  Wisconsin  experiment  station  and 
was  first  extensively  applied  and  confirmed  by  the 
work  of  the  New  York  experiment  station. 

This  method  is  based  upon  the  following  facts: 
( i )  Milk- fat  is  capable  of  holding  mechanically 
one-tenth  of  its  own  weight  of  water.  This  has 
been  already  explained  in  detail  in  connection  with 
the  discussion  of  method  2.  (2)  The  reason  for  mul- 
tiplying the  amount  of  casein  in  milk  by  2.5  is 
found  in  the  yield  of  cheese  from  skim-milk  and 
also  in  the  results  of  some  experimentar  work  done 
at  the  New  York  experiment  station.  A  prepara- 
tion of  pure  casein  was  made,  dried,  and  then  al- 
lowed to  absorb  as  much  water  as  it  would  be 


CALCULATING   YIELD   OF    CHEESE  217 

likely  to  hold  in  being  made  into  green  cheese.  It 
was  found  that  one  pound  of  casein  takes  up  water 
enough  to  increase  its  weight  to  2.25  pounds.  If 
to  this  is  added  the  amount  of  ash  constituents 
taken  up  in  the  same  amount  of  cheese,  the  weight 
is  increased  to  just  about  2.5  pounds.  This  method 
has  the  following  defects:  (i)  As  already  pointed 
out,  the  calculation  of  the  amount  of  cheese  yield 
coming  from  milk-fat  is  too  high  when  there  are 
abnormal  losses  of  fat  in  cheese-making.  (2) 
When  the  yield  of  cheese  is  calculated  by  this 
method,  the  percentage  of  water  in  cheese  is  not 
uniform,  but  varies  with  the  percentage  of  casein 
in  milk,  because  the  water  content  of  the  cheese  is 
made  dependent  largely  upon  the  amount  of  casein. 
The  inevitable  result  is  that  in  case  of  milks 
containing  high  percentages  of  casein  in  relation  to 
fat,  the  percentage  of  water  is  greater  in  the  cheese 
calculated  by  this  method  than  in  case  of  cheese 
from  milks  in  which  the  amount  of  casein  is  lower 
in  relation  to  fat.  When  the  ratio  of  fat  and  casein 
is  fairly  constant,  the  results  are  quite  satisfactory. 
The  manner  in  which  this  method  of  calculation 
favors  the  yield  of  cheese  in  case  of  milk  low  in  fat 
and  relatively  high  in  casein  as  against  the  yield 
of  cheese  in  case  of  milk  high  in  fat  and  relatively 
low  in  casein  can  be  illustrated  by  the  data  in  the 
table  on  the  next  page. 

Attention  is  called  to  the  following  facts  in 
connection  with  the  data  contained  in  this  table : 
(i)  When  the  cheese  made  from  the  two  differ- 
ent milks  contains  the  same  amount  of  water  (37 
per  cent),  the  water  in  the  cheese  made  from  100 
pounds  of  milk  amounts  to  3.31  pounds  in  the  case 


21 8     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


of  the  cheese  made  from  the  poorer  milk  and  5.31 
pounds  in  the  case  of  the  cheese  made  from  the 
richer  milk.  When  the  cheese  from  the  two  milks 
is  made  to  contain  the  average  amount  of  water 
(37  per  cent)  found  in  green  cheese,  there  is  a 
normal  difference  of  2  pounds  of  water  in  the 
cheese  made  from  100  pounds  of  milk.  What  do 
we  find  in  regard  to  the  yield  of  cheese  and  of 
water  in  the  cheese,  when  the  yield  of  cheese  is 
calculated  by  method  3?  The  yield  of  cheese  from 
100  pounds  of  the  poorer  milk  is  increased  0.19 
pound,  from  8.90  to  9.09  pounds,  an  increase  wholly 


Per  cent 
of  fat 
in 
milk 

Per  cent 
of 
casein 
in  milk 

Pounds  of 
cheese 
(containing 
37  per  cent 
of  water) 
made  for 
100  pounds 
of  milk 

Pounds 
of  water 
in  cheese 
made 
from   100 
poxinds 
of  milk 

Pounds  of 
cheese  for 
100  pounds 
of  milk 
calculated 
by 
method  3 

Pounds  of 
water  in 
cheese 
from  100 
pounds  of 
milk 
(method  3) 

Per  cent  of 
water  in 
cheese  cal- 
culated by 
method  3 

3.26 
5.78 

2.20 
3.03 

8.90 
14.36 

3.31 
5.31 

9.09 
13.93 

3.50 
4.88 

38.50 
35.00 

due  to  the  greater  amount  of  water  contained  in 
the  cheese;  the  water  increases  from  3.31  to  3.50 
pounds,  and  the  percentage  of  water  in  the  cheese, 
from  37  to  38.50.  In  the  case  of  the  cheese  made 
from  the  richer  milk,  the  reverse  is  found  to  be 
true.  The  yield  of  cheese  containing  37  per 
cent  of  water  is  14.36  pounds  for  100  pounds  of 
milk,  and  this  is  decreased  0.43  pound  or  from 
14.36  to  13.93  pounds.  This  decrease  is  wholly 
due  to  the  smaller  amount  of  water  in  the  cheese 
when  the  yield  is  calculated  by  method  3.  Thus, 
the  amount  of  water  in  the  cheese  containing  37 


CALCULATING   YIELD   OF    CHEESE  2 19 

per  cent  of  water  is  decreased  from  5.31  to  4.88 
pounds  in  the  cheese  calculated  by  method  3,  and 
the  percentage  of  water  from  37  to  35  per  cent. 
We  see,  therefore,  that  the  difference  of  cheese 
yield  in  these  two  cases  should  be  normally  5.46 
pounds  for  the  cheese  made  from  100  pounds  of 
milk,  but  the  difference  is  only  4.86  pounds,  or 
0.62  pound  too  small,  when  the  yield  is  calculated 
by  method  3.  (3)  Another  objection  raised  to 
this  method  is  that,  under  ordinary  conditions,  the 
percentage  of  casein  in  milk  is  not  known  and  the 
method  is  consequently  inapplicable.  In  reply  to 
this,  the  percentage  of  casein  in  milk  can  be  calcu- 
1ated  from  the  percentage  of  milk-fat  and  the  method 
carried  out  in  the  usual  way.  Even  when  the  amount 
of  casein  in  milk  is  calculated,  the  results  are  gen- 
erally much  more  accurate  than  those  given  by  method 
2  (i.i  FaH-5-9). 

METHOD    BASED    ON    FAT    AND    SOLIDS- 
NOT-FAT  IN  MILK     (4) 

In  the  twelfth  annual  report  of  the  Wisconsin 
experiment  station  there  is  a  detailed  discussion  of 
the  facts  leading  to  the  proposal  of  the  following 
formula : 

Yield  of  green  cheese  containing  37  per  cent  of 
water 

^Solids-not-fat    +  0.91  Pat  )  x  j.jg 

This  formula  is  based  on  the  following  details:  (i) 
The  amount  of  solids-not-fat  in  100  pounds  of  milk, 
divided  by  3,  represents  the  amount  of  milk-solids, 
other  than  fat,  available  for  cheese,  including  added 


22O    SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

salt  in  cheese ;  it  therefore  includes  milk-casein  and 
ash  constituents.  (2)  The  average  amount  of  fat 
lost  in  cheese-making  is  taken  as  9  per  cent  of  the 
milk- fat  and,  consequently,  0.91  of  the  milk-fat  is 
calculated  as  being  in  the  cheese.  (3)  In  using  the 
factor  1.58,  the  cheese-solids  are  calculated  to  an 
equivalent  amount,  of  cheese  containing  37  per  cent 
of  water.  This  method  has  been  supposed  to  give 
more  accurate  results  than  any  of  the  preceding 
methods. 

The  following  objections  to  the  method  suggest 
themselves :  ( i )  It  involves  the  accurate  determina- 
tion of  the  specific  gravity  of  milk  in  addition  to 
the  percentage  of  milk-fat.  This  ought  not  to  be 
a  serious  objection,  but  is  found  to  be  so  practically 
when  cheese-makers  try  to  find  time  to  take  the 
necessary  lactometer  readings.  (2)  The  formula  is, 
more  complicated  than  any  other,  requiring  more 
extended  arithmetical  work,  although  entirely  of  a 
simple  kind.  (3)  The  accuracy  of  calculating  the 
non-fat  cheese-solids  as  equal  to  one-third  of  the 
solids-not-fat  of  milk  is  not  as  close  as  is  desirable, 
because,  when  applied  in  the  case  of  different  milks, 
the  results  are  found  to  be  quite  irregular  outside 
of  certain  limits,  to  which  attention  will  be  called 
later. 

NEW     METHOD     BASED     ON     FAT     AND 
CASEIN  IN  MILK     (5) 

On  account  of  difficulties  experienced  in  applying 
the  methods  under  consideration  with  uniform  and 
accurate  results,  an  effort  has  been  made,  based  on 


CALCULATING   YIELD   OF    CHEESE  221 

the  results  of  the  work  done  at  the  New  York  ex- 
periment station,  to  work  out  a  method  of  deter- 
mining cheese  yield  which  should  be  simple  and 
at  the  same  time  more  accurate  than  the  methods 
previously  used.  This  method  is  based  upon  (i) 
the  per  cent  of  fat  and  of  casein  in  milk;  (2)  a  loss 
of  fat  proportional  to  the  amount  of  fat  in  milk, 
based  upon  average  results;  (3)  a  uniform  loss  of 
casein;  (4)  an  amount  of  salts  and  albumin  in  cheese 
proportional  to  the  available  fat  and  casein  in 
the  milk;  and  (5)  a  uniform  percentage  of  water  in 
cheese. 

We  will  now  briefly  consider  the  details  upon 
which  the  method  is  based,  under  the  two  following 
divisions:  (i)  Calculation  of  cheese-solids,  and  (2) 
calculation  of  water  in  cheese.  The  amount  of 
solids  in  cheese  is  calculated  by  the  formula, 
(0.93 Fat -j- Casein  —  0.10X1.09.  This  is  based  upon 
the  following  details :  ( i )  Of  the  fat  in  milk,  7  per 
cent  (0.07  pound  for  each  pound  of  milk-fat)  is  lost 
in  whey  and  93  per  cent  (0.93  pound  for  each 
pound  of  milk- fat)  remains  in  cheese  (p.  190). 
(2)  Of  the  milk-casein,  about  o.io  pound  for  100 
pounds  of  milk  is  lost,  the  rest  going  into  the 
cheese  (p.  195).  (3)  The  other  constituents  of 
cheese-solids,  consisting  mostly  of  salts  (p.  187), 
form  about  9  per  cent  (0.09)  of  the  fat  and  casein 
present  in  cheese.  Therefore,  if  we  multiply  the 
amount  of  fat  and  casein  in  cheese  by  1.09  we  ob- 
tain the  total  amount  of  cheese-solids  (fat,  casein, 
salts,  etc.)  in  cheese.  For  example,  suppose  we* have 
milk  containing  4  per  cent  of  fat  and  2.5  per  cent  of 
casein,  how  many  pounds  of  cheese-solids  can  be 


222     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

made  from  100  pounds  of  such  milk?  Using  the 
formula,  we  have  [0.93X4  (fat)H~2-5  (casein)  — 
o. io]X  i. 09=  ( 3.72+2.40 )X  i. 09=6.67  pounds. 

It  remains  now  simply  to  calculate  the  cheese- 
solids  into  cheese  with  a  given  percentage  of  water. 
This  can  be  done  by  subtracting  from  i.oo  the  per- 
centage of  water  desired  in  the  cheese,  expressed  as 
hundredths,  and  then  dividing  by  the  result  the  solids 
in  the  cheese,  as  obtained  above.  The  formula,  thus 
amended,  becomes: 

(0.93  Fat  +  Casein  -  0.10)  x  1.09 

100  -  W  (water  in  cheese) 

Continuing  the  illustration  in  which  we  have  found 
6.67  pounds  of  cheese-solids,  we  will  suppose  that  we 
wish  to  know  how  much  cheese,  containing  37  per 
cent  of  water,  can  be  made  from  this  amount  of 
cheese-solids.  We  simply  divide  6.67  by  0.63  (i.oo — 
0.37),  which  gives  10.6  pounds.  To  find  the  equiv- 
alent amount  of  cheese  containing  35  per  cent  of 
water,  divide  by  65  (i.oo — 0.35);  for  cheese  con- 
taining 40  per  cent  of  water,  divide  cheese-solids  by 
0.60  (i.oo — 0.40). 

If,  then,  we  wish  to  have  a  method  for  calculating 
yield  of  cheese  when  the  cheese  contains  a  definite 
amount  of  water,  say  37  per  cent,  which  is  the  average 
amount  in  green  cheddar  cheese,  we  can  use  the 
formula : 

(0.93  Fat  +  Casein  -  0.10)  X  1.09 
0.63 

This  can  be  further  simplified  by  dividing  1.09  by 
0.63,  when  the  formula  becomes 

(0.93  Fat+Casein — o.io)Xi73. 
In   other  words,  find,   in  the  manner  indicated,  the 


CALCULATING    YIELD   OF    CHEESE  223 

amount  of  fat  and  casein  that  go  into  the  cheese  and 
multiply  by  1.73. 

After  satisfactorily  applying  the  formula  in  this 
form  to  a  large  number  of  cases,  it  occurred  that 
this  might  be  used  as  a  means  of  working  out  a 
still  simpler  relation  between  the  fat  and  casein 
of  milk  and  yield  of  cheese.  Using  the  foregoing 
formula  for  calculating  the  cheese  yield  with  milks 
covering  quite  a  wide  variation  in  percentages  of  fat 
and  of  casein,  it  was  found  that  the  formula  could  be 
simplified  to  the  following  form  : 

(5)  (Fat-f-casein)Xi-63=yield  of  cheese 
for  loo  pounds  of  milk,  the  cheese  containing  37  per 
cent  of  water.  Stated  in  the  form  of  a  rule,  this 
becomes :  Add  together  the  numbers  representing  the 
percentages  of  fat  and  of  casein  in  milk  and  multiply 
the  sum  by  1.63. 

From  this  formula,  we  can  calculate  in  the  fol- 
lowing manner  the  equivalent  amount  of  cheese 
containing  any  percentage  of  moisture.  Multiply 
the  cheese  yield,  calculated  according  to  the  last 
formula,  by  0.37;  subtract  this  amount  from  the 
weight  of  cheese  and  divide  the  remainder  by  i.oo 
minus  the  number  expressing  the  desired  percent- 
age of  moisture.  Expressed  as  a  formula,  this 
becomes : 

P  (Number  of  pounds  of  cheese)  -  0.37  P 

100  -  W  (percentage  of  water  desired^ 

For  convenience,  we  have  thus  calculated  a  fac- 
tor which  can  be  used  directly  in  determining 
cheese  yield  for  each  percentage  of  water  from  30 
to  50. 


224     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

SIMPLE      METHOD       OF      CALCULATING 
CHEESE     YIELD     FOR     CHEESE     CON- 
TAINING    DIFFERENT     PERCENT- 
AGES OF  WATER 

In  order  to  obtain  the  amount  of  cheese  yield  con- 
taining a  given  percentage  of  water,  substitute  the 
number  opposite  the  given  percentage  in  the  following 
list  for  1.63  in  the  last  formula  above  given,  which 
would  then  become : 

Yield=(Fat-j-Casein)  XN 

(N  being  the  number  in  the  following  list  which  cor- 
responds to  the  percentage  of  water  in  cheese  desired). 


Per  cent  of  water 
in  cheese 

Factor  to  be  used 
as  N  in  formula  (Fat  +  casein)  X  N 

30 

1.47 

31 

1.49 

32 

1.51 

33 

1.53 

34 

1.555 

35 

1.58 

36 

1.605 

37 

1.63 

38 

1.655 

39 

1.68 

40 

1.71 

41 

42 

1  77 

43 

l'.80 

44 

1.835 

45 

1.87 

46 

1.90 

47 

1.94 

48 

1.98 

49 

2.015 

50 

2.05 

SIMPLE      METHOD      FOR      CALCULATING 

YIELD  OF  CHEESE  FROM  FAT  AND 

CALCULATED   CASEIN 

In  connection  with  the  foregoing  method,  which 
is  based  in  part  upon  the  percentage  of  casein  in 
milk,  it  may  be  objected  that  the  method  cannot  be 


CALCULATING    YIELD   OF    CHEESE  225 

applied  when  we  do  not  know  the  percentage  of 
milk-casein.  In  reply  to  this,  it  can  be  stated  that 
fairly  accurate  results'  can  be  obtained  by  calculat- 
ing the  amount  of  casein  in  milk  from  the  formula: 
Per  cent  of  casein  in  milk=(Fat — 3)Xo.4+2.i 
(p.  170). 

This  formula  can  be  combined  with  the  follow- 
ing formula:  Cheese  yield=(Fat+Casein)Xi-63 
and  the  two  operations  of  calculating  casein  and 
cheese  yield  can  be  combined  in  one  simple  formula, 
as  follows: 

(6)     Cheese  yield=2.3F-f-i.4. 

Therefore,  in  multiplying  the  per  cent  of  fat  in  milk 
by  2.3  and  adding  1.4  to  the  result,  we  obtain  directly 
the  yield  of  cheese,  containing  37  per  cent  of  water, 
based  on  the  percentage  of  milk-fat  and  the  amount 
of  casein  corresponding  to  this  percentage  of  fat,  as 
found  by  the  milk-casein  formula. 

The  yield  of  cheese  corresponding  to  any  per- 
centage of  water  from  30  to  50  can  be  similarly  cal- 
culated. This  is  done  by  substituting  for  N  in  the 
following  formula  one  of  the  numbers  in  the  last  table 
preceding,  according  to  the  desired  percentage  of 
water:  (1.4  Fat+O-9)XN. 

METHOD    OF    CALCULATING    YIELD    OF 
RIPE  CHEESE 

The  amount  of  moisture  in  cheese  when  it 
is  sold  for  consumption  necessarily  varies  with 
a  number  of  different  conditions  (p.  315) .  and  an 
effort  to  estimate  the  amount  of  cheese  yield  in 
marketable  condition  is,  to  some  extent,  a  matter 
of  guesswork,  unless  one  knows  something  of  the 


226     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

conditions  of  temperature,  moisture,  etc.,  under 
which  the  cheese  has  been  kept  However,  it  is 
sometimes  desired  to  know  approximately  the  yield 
of  ripened  cheese.  We  can  assume  (i)  that  the 
green  cheese  contains  an  average  percentage  of 
water  (37)  and  (2)  that  it  loses  5  pounds  of  water 
for  loo  pounds  of  cheese.  This  would  have  the 
effect  of  reducing  the  percentage  of  water  in  the 
ripe  cheese  to-  about  34.  Therefore,  the  simplest  way 
to  calculate  the  amount  of  ripe  cheese,  if  the  com- 
position of  the  milk  is  known,  is  to  multiply  the  sum 
of  the  percentage  of  fat  and  casein  in  milk  by  1.555; 
or,  when  only  the  per  cent  of  fat  in  milk  is  known,  to 
multiply  the  fat  by  2.2  and  then  add  1.3. 

COMPARISON     OF     ACCURACY     OF     DIF- 
FERENT  METHODS    OF    CALCULAT- 
ING CHEESE  YIELD 

In  making  a  comparative  study  of  the  accuracy 
of  the  different  methods  that  have  been  used  or 
proposed  for  calculating  yield  of  cheese,  the  follow- 
ing procedure  was  adopted:  As  a  basis  upon  which 
to  work,  there  were  taken  200  of  the  experiments 
contained  in  the  records  of  the  New  York  experi- 
ment station,  which  give  full  analyses  of  milk, 
whey  and  cheese,  and  yields  of  cheese.  The  yields 
of  cheese  as  given  were  calculated  to  a  uniform 
basis  of  cheese  containing  37  per  cent  of  water. 
The  yield  of  cheese  was  then  calculated  according 
to  each  one  of  the  formulas  that  have  been  discussed. 
In  the  case  of  the  methods  in  which  casein  is  a 


CALCULATING    YIELD    OF    CHEESE 

factor,  the  yield  of  cheese  was  calculated  both  for 
the  actual  amount  of  casein  in  the  milk  as  obtained 
by  analysis  and  for  the  calculated  amount  of  casein 
as  obtained  by  the  casein  formula.  There  were 
thus  compared,  in  reality,  seven  different  methods. 
It  is  impracticable  to  give  these  results  in  detail, 
but  it  will  be  found  sufficient  to  present  them  in 
the  form  of  tabulated  summaries.  It  has  been 
found  that  the  most  effective  means  of  compari- 
son is  to  divide  the  experiments  into  several 
groups  based  on  the  percentage  of  fat  in  milk,  and 
under  each  group  to  indicate  the  number  of  cases 
in  which  the  results  differ,  within  certain  limits, 
from  the  actual  yield  of  cheese.  To  illustrate,  we 
will  take  Group  I  (p.  228),  including  22  experiments, 
in  which  milk  containing  3  to  3.49  per  cent  of  fat  was 
used.  In  the  case  of  method  i  (FatX2-7),  there  are 
20  cases  out  of  the  22  in  which  the  calculated  yield 
of  cheese  is  within  0.25  pound  (4  ounces)  of  the 
actual  yield.  There  are  2  cases  in  which  the  calculated 
yield  is  within  0.26  to  0.35  pound  of  the  actual  yield. 
In  the  case  of  formula  2,  there  are  only  5  cases  in 
which  the  calculated  yield  is  within  a  quarter  of  a 
pound  of  the  actual  yield,  etc. 

A  study  of  the  table  on  page  228  enables  one  to 
observe  the  truth  of  the  following  statements: 

The  different  methods  in  some  cases  show  great 
variation  in  respect  to  accuracy,  according  to  the 
composition  of  the  milk.  Thus,  method  i  (FatX 
2.7),  which  has  usually  been  regarded  as,  perhaps, 
the  least  accurate  of  any  method  in  use,  is  found 
to  give  most  excellent  results  in  the  case  of  milks 


228     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


COMPARISON  OF  DIFFERENT  METHODS  FOR  CALCULATING 
CHEESE    YIELD 


Group  I 
22  Exp'ts 
Fat  3-3.49% 

Variation 
from 
actual  yield 

0-0.25  Ib. 
0.26-0.35  Ib. 
0.36-0.50  Ib. 
0.51-0.75  Ib. 
0.  76-1.00  Ib. 

1 

t^ 

cs 
M 

1 

2 

°i 

»o 

+ 

1 

3 

1.1  Fat  +  2.5 
Casein 

4 

00 

X 

&r 

Os 

+  "» 

q 

M 

(Fat  +  Casein) 
X  1.63  o, 

(Actual  casein) 

2.3  F+  1.4 

Os 

(Calculated  casein) 

Actual 
casein 

Calculated 
casein 

20 

2 

5 
2 
7 
7 
1 

10 

4 
7 

1 

11 
9 
2 
0 

5 
10 
5 
2 

19 
2 
1 

21 

1 

Group  II 
59  Exp'ts 
Fat  3.50-3.74 
0-0.25  Ib. 
0.26-0.35  Ib. 
0.36-0.50  Ib. 
0.51-0.75  Ib. 

34 
10 
8 
7 

43 
3 
10 
2 

43 
12 
3 
1 

40 
9 
7 
3 

48 
3 

49 
6 
4 

29 
13 
9 
8 

Group  III 
51  Exp'ts 
Fat  3.  75-3.99 
0-0.25  Ib. 
0.26-0.35  Ib. 
0.36-0.50  Ib. 
0.51-0.75  Ib. 
0.75-0.99  Ib. 

33 
8 
9 

1 

29 
6 
12 
3 

35 
3 
6 
6 
1 

32 

12 
7 

38 
7 
5 

1 

37 
7 

5 
2 

31 
10 
9 

1 

Group  IV 
43  Exp'ts 
Fat  4.  0-4.  19 
0-0.25  Ib. 
0.26-0.35  Ib. 
0.36-0  50  Ib. 
0.51-0.75  Ib. 
0.75-0.99  Ib. 
1.00-l.SOlb. 

20 
9 
9 

t 

8 
13 
9 
4 
5 
7 

29 
5 
6 
2 
1 

27 
3 
4 
6 
3 

20 
8 
5 

4 
6 

35 
4 
3 
1 

29 

3 
6 
4 

Group  V 
25  Exp'ts 
Fat  4.2-4.4 
0-0.25  Ib. 
0.26-0.35  Ib. 
0.36-0.50  Ib. 
0.51-0.75  Jb. 
0.75-0.90  Ib. 
1.00-1.50  Ib. 

13 
5 
5 
2 

0 
0 
1 
11 

4 
9 

16 
4 
2 
2 

1 

15 

1 
5 
4 

4 
4 
8 
7 
2 

20 

1 

15 
1 
4 

5 

varying  in  fat  from  3.0  to  3.50  per  cent,  and  compara- 
tively fair  results  in  the  case  of  milks  containing  fat 
up  to  4.0  per  cent.  Method  2  (i.i  Fat+5-9)  gives 


CALCULATING   YIELD   OF    CHEESE  229 

fairly  good  results  in  case  of  milks  containing  3.50 
to  3.75  per  cent  of  fat,  because  the  casein  of  such 
milks  is  near  the  average  upon  which  this  formula 
is  really  based  (p.  215)  ;  but,  outside  of  these  nar- 
row limits,  it  is  the  least  accurate  of  all  the  methods 
that  have  been  used  or  proposed.  In  case  of  milk 
containing  4.0  per  cent  of  fat  or  more,  the  method  is 
entirely  useless,  in  some  cases  varying  from  the 
real  yield  of  cheese  I  to  1.5  pounds.  Method  3 
(i.i  Fat-j-2-5  Casein),  when  the  actual  amount  of 
casein  is  known,  gives  rather  poor  results  in  case  of 
milk  below  3.5  per  cent  in  fat,  excellent  results 
when  the  per  cent  of  fat  in  milk  ranges  from  3.5  to 
4.0  per  cent,  fairly  good  results  in  case  of  milk  con- 
taining as  high  as  4.2  per  cent  of  fat,  but  less  accurate 
with  milks  above  this.  Method  3,  when  the  casein  i? 
calculated,  gives  results  which  are,  in  general,  in  verj 
good  agreement  with  those  obtained  when  the 
amount  of  casein  is  determined  by  chemical  analysis. 
Method  4 

(gglids3not-fat  +  0.91  F)X  1.58. 

gives  most  excellent  results  when  the  milk  con- 
tains 3.50  to  4.0  per  cent  of  fat,  but  in  other  cases 
is,  with  the  exception  of  method  2,  the  least  accu- 
rate of  any  examined.  This  method  has  heretofore 
had  the  reputation  of  being,  for  all  grades  of  milk, 
the  most  accurate  method  in  use.  Method  5,  when 
the  per  cent  of  casein  in  milk  is  known,  is  seen  to 
be  the  most  accurate  method  of  all.  When  the 
casein  is  calculated,  method  6  gives  excellent  com- 
parative results,  the  least  satisfactory  being  in  the 
case  of  milks  containing  3.50  to  3.75  per  cent  of 


230     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


fat.     In  the  case  of  milks   containing  3   to   3.50  per 
cent  of  fat  the  results  are  most  excellent. 

The  following  table  gives  a  summary  of  the  results, 
showing  the  percentage  of  cases  in  which  the  different 
methods  are  accurate  within  the  limits  designated, 
taking  all  the  200  results  into  consideration  without 
reference  to  special  groups  in  respect  to  percentage 
of  milk-fat : 


1 

• 

Actual 
casein 

3 
Calculated 
casein 

4 

5 

Actual 
casein 

6 

Calculated 
casein 

0-0.25 
0.26-0.35 
0.36-0.50 
0.51-0.75 
0.76-0.99 
1.00-1.50 

60. 
17. 
15.5 
7. 
0.5 
0. 

42.5 
12. 
19.5 
13.5 
4.5 
8. 

66.5 
14. 
12. 
6. 
1.5 
0. 

62.5 
17. 
12.5 
6.5 
1.5 
0. 

57.  5 
18. 
12. 
8.5 
4. 
0. 

80 
10 
7 
3 
0 
0 

62.5 
13. 
12.5 
10. 
2. 
0. 

From  these  results,  the  relative  values  of  the  dif- 
ferent formulas  can  be  judged  in  a  general,  compara- 
tive way.  It  is  evident  that  method  2  (i.i  Fat+5.9) 
should  not  be  used  and  that  method  4, 

^Solids-not-fat  +  .91Fat)xl.sg 

should,  if  employed  at  all,  be  used  only  in  the  case 
of  milks  containing  3.5  to  4.0  per  cent  of  fat.  When 
the  percentage  of  casein  in  milk  is  known,  only 
method  5  (Fat -(-Casein) XL 63  should  be  used.  In 
case  the  casein  has  to  be  calculated  from  the  per- 
centage of  fat  in  milk,  then  method  6  should  be  used. 
For  ordinary  purposes  method  6  will  probably  be 
found  to  be  the  most  useful,  since  the  only  factor 
needed  is  the  percentage  of  milk-fat  and  the  calcula- 
tion is  extremely  simple  (2.3  Fat -(-1.4). 


CHAPTER  XIX 

Milk  Constituents  in  Relation  to  Compo- 
sition of  Cheese 

While  the  yield  of  cheese  from  100  pounds  of  milk 
depends,  as  has  been  shown  (p.  186),  upon  the 
amount  of  fat,  casein  and  insoluble  salts  in  milk,  so 
far  as  the  cheese-solids  are  concerned,  the  percentage 
composition  of  the  cheese-solids  depends  practically 
upon  the  relation  of  fat  and  casein  in  milk.  Milk 
rich  in  fat,  as  compared  with  milk  poor  in  fat, 
usually  produces  cheese  containing  more  fat  in  pro- 
portion to  other  constituents.  The  composition  of 
cheese  depends  primarily  upon  the  composition 
of  the  milk  used,  provided  the  process  of  cheese-mak- 
ing is  performed  in  a  normal  manner,  so  as  to  avoid 
excessive  loss  of  fat  or  casein.  In  this  connection 
we  shall  discuss  the  following  points:  (i)  The  rela- 
tion of  composition  of  milk  to  composition  of 
cheese  (a)  in  case  of  normal  milk,  (b)  in  case 
of  skimmed  milk,  and  (c)  in  case  of  milk  containing 
added  cream.  (2)  The  United  States  standard  for 
cheese. 

MILK  CONSTITUENTS  AND  COMPOSITION 
OF  CHEESE 

Composition  of  cheese  from  normal  milk. — The 
composition  of  green  cheese,  in  case  of  normal  fac- 
tory milk,  as  made  in  New  York  state,  shows  the 


232     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

following  range  of  variations  and  general  average, 
as  the  result  of  the  extended  investigations  carried  on 
by  the  New  York  experiment  station : 


Lowest 

Highest 

Average 

Water 

32  69 

43  89 

36  84 

Total  solids.  .  . 

56.11 

67.31 

63.16 

Fat  

JO.  00 

36  79 

33  83 

Proteins 

20  80 

26  11 

23  72 

Salts,  etc.  (represented  in  ash)  

3.12 

7.02 

5.61 

Percentage  of  solids  in  form  of  fat  ... 
Ratio  of  fat  to  proteins  

50.39 
1:0.79 

56.83 
1  :0.63 

53.56 
1:0.70 

We  can  illustrate  differences  in  composition  of 
cheese  made  from  normal  milk  by  taking  cheese 
made  from  the  milk  of  different  breeds  of  cows. 
For  this  purpose,  we  will  use  the  composition  of 
milk  as  given  on  p.  165  in  case  of  four  different 
breeds : 


Breed 

Solids 
in 
cheese 

Fat  in 
cheese 

Proteins 
in 
cheese 

Percentage 
of  total  solids 
in  form 
of  fat 

Ratio  of 
fat  to 
proteins 

Holstein-Friesian 
Ayrshire  
Guernsey  .  . 

Per  cent 
63.00 
63.00 
63.00 

Per  cent 
34.1 
34.5 
37.0 

Per  cent 
23.6 
23.3 
20.8 

54.3 
54.8 
58  7 

Fat  :  Proteins 
1:  0.69 
1:  0.67 
1:  0  56 

Jersey 

63  00 

37  5 

20  4 

600 

1;  0  54 

The  difference  in  composition  is  very  clearly 
seen,  especially  if  we  notice  the  percentage  of 
the  cheese-solids  present  in  the  form  of  fat  and  the 
ratio  of  fat  to  proteins  as  shown  in  the  last  two 
columns.  In  connection  with  this  table,  study  Fig. 
37  (p.  208). 


MILK    AND    COMPOSITION    OF    CHEESE 


233 


The  following  table  extends  the  illustration  sys- 
tematically to  ordinary  milks  containing  different 
percentages  of  fat.  We  may  regard  these  as  rep- 
resenting milks  of  different  herds.  See  also  Fig.  36. 


Per  cent 
of  fat 
in.  milk 

Cheese- 
solids 

Fat  in 
cheese 

Proteins 
in  cheese 

Percentage 
of  total 
solids  in 
form  of  fat 

Ratio  of 
fat  to 
proteins 

Per  cent 

Percent 

Per  cent 

Fat  :  Proteins 

3.00 

63.00 

33.7 

24.1 

53.5 

1:  0.72 

3.25 

34.1 

23.7 

54.0 

1:  0.70 

3.50 

34.5 

23.3 

54.6 

1-  0.68 

3.75 

34.8 

23.0 

55.2 

I!  0.66 

4.50 

35.1 

22.7 

55.7 

i:  0.65 

4.25 

35.4 

22.4 

56.2 

1  :  0.63 

4.50 

•• 

35.7 

22.1 

56.7 

l:  0.62 

These  tables  strikingly  indicate  that,  as  milk  in- 
creases in  percentage  of  fat,  the  cheese  made  from 
such  milk  increases  in  percentage  of  fat  and  de- 
creases in  percentage  of  proteins.  The  composi- 
tion of  the  cheese-solids  follows  the  composition  of 
the  milk  as  shown  in  the  relation  of  fat  and  pro- 
teins. 

Composition  of  cheese  made  from  skimmed 
milk. — The  removal  of  fat  from  milk  reduces  the 
amount  of  fat  in  relation  to  casein,  because,  in 
skimming  milk,  only  a  relatively  small  amount  of 
casein  is  removed  with  the  fat.  The  remaining 
skim-milk  is  therefore  richer  in  casein  relative  to 
fat,  the  ratio  increasing  with  the  amount  of  fat 
removed.  The  effect  of  skimming  milk  upon  its 
composition  and  upon  the  composition  of  cheese 
is  illustrated  in  the  two  following  tables.  The 
data  are  based  upon  (i)  normal  milk  containing  4 
per  cent  of  fat,  (2)  removal  of  fat  alone  without 


234     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

other  constituents,  (3)  a  uniform  percentage  of 
casein  in  skim-milk,  and  (4)  a  uniform  per  cent  (37) 
of  water  in  cheese.  While  the  data  represent 
theoretical  conditions,  the  results  are  not  far  from  the 
truth  in  practical  application  and  they  serve  satisfac- 
torily to  illustrate  the  point  we  desire  to  impress  In 
connection  with  this  table,  study  Fig.  38. 

EFFECT  OF  SKIMMING    MILK   ON    COMPOSITION    OF   MILK 
AND  YIELD  OF  CHEESE 


Pounds  of  fat 

Pounds  of  fat 

Pounds    of 

Ratio  of  fat 

Pounds 

removed  from 

left  in 

casein  in 

to  casein 

of 

100  pounds 

skimmed 

skimmed. 

in  milk 

cheese 

of  milk 

milk 

milk 

Fat:  Casein 

ft)—  0.00 

4.00* 

2.50 

1    0.63 

10.60 

(2)—  0.50 

3.50 

2.50 

1     0.71 

9.79 

(3)—  1.00 

3.00 

2.50 

1     0.83 

8.98 

(4)—  2.00 

2.00 

2.50 

1     1.25 

7.37 

(5)—  3.00 

1.00 

2.50 

1     2.50 

5.71 

(6)—  3.90 

o.iot 

2.50 

1     25.0 

4.33 

*Normal  milk.         fSeparator  skim-milk. 


EFFECT    OF    SKIMMING    MILK    ON    COMPOSITION    OF 
CHEESE 


Per  cent  of  fat 
in  cheese 

Per  cent  of 
proteins  in 
cheese 

Percentage  of 
cheese-solids  in 
form  of  fat 

Ratio  of  fat 
to  proteins  in 
cheese 

(1)—  35.1 
(2)—  33.3 
(3)—  31.1 
(4)—  25.2 
(5)—  16.1 
(6)—  2.3 

22.7 
24.5 
26.7 
32.6 
41.7 
55.5 

55.7 
53.0 
49.4 
40.0 
25.5 
3.7 

Fat:  Proteins 
1:  0.65 
1-  0.74 
1:  0.86 
1:  1.30 
1:  2.60 
I:  24.00 

In     making    cheese     from     skim-milk,     the    yields 
given  are  lower  than  those  obtained  in   commercial 


MILK    AND    COMPOSITION    OF    CHEESE 


235 


work,  because  here  we  allow  for  only  37  per  cent 
of  water,  while  commercial  skim-milk  cheese  never 
contains  so  little  moisture,  but  usually  from  40  to 
55  per  cent,  the  moisture  held  in  cheese  increasing 


FIG.   38 — DIAGRAM   SHOWING    EFFECT   OF   SKIMMING   MILK 
UPON  THE  YIELD  AND  COMPOSITION  OF  CHEESE 

The  figures  immediately  above  each  column  give  the  number  of  pounds  of 
cheese  (containing  37  per  cent  of  water)  made  from  100  pounds  of  milk.  The  figures 
within  the  diagram  give  the  pounds  of  each  constituent  in  cheese.  The  figures 
at  the  top  of  the  diagram  give  the  percentage  of  fat  in  milk  and  skim-milk. 

as  the  per  cent  of  fat  in  skim-milk  decreases.  In  com- 
paring the  results  in  this  table  with  those  in  the 
table  on  p.  232,  in  which  the  composition  is  shown 
of  cheese  made  from  milk  low  and  high  in  fat, 
we  see  that  the  difference  there  is  the  same  in 


236     SCIENCE    AND     PRACTICE    OF    CHEESE- MAKING 

character  as  that  brought  about  by  partially  skim- 
ming whole  milk.  For  example,  by  skimming  from 
100  pounds  of  Jersey  milk,  containing  5.78  per  cent 
of  fat,  1.25  pounds  of  fat,  thus  reducing  the  fat  to 
4.53  per  cent,  the  resulting  milk  and  cheese  will  then 
be  essentially  the  same  in  composition,  in  relation  to 
cheese-solids,  as  the  normal  Holstein-Friesian  milk, 
as  shown  by  the  following  table: 


Per  cent 
of  fat 

Per  cent 
of  casein 

Ratio  of  fat 
to  casein 

Holstein-Friesian  milk  

3.26 

2.20 

Fat  :  Casein 
1:  0.67 

Jersey  milk  (normal)                        .  .  . 

5  78 

3  03 

1  :  0.52 

Jersey  milk  (partially  skimmed)  

4.53 

3.03 

1:  0.67 

Of  course,  the  same  result  could  be  accomplished 
by  adding  skim-milk  to  milk  rich  in  fat. 

There  is  another  way  of  comparing  milks  which, 
like  these,  are  poor  and  rich  in  fat.  Thus,  how 
much  fat  would  it  be  necessary  to  add  to  the  Hol- 
stein-Friesian milk  to  have  it  make  cheese  like  that 
made  from  Jersey  milk?  Calculation  shows  that 
nearly  one  pound  of  fat  would  need  to  be  added 
to  100  pounds  of  the  Holstein  milk,  which  is  thus 
shown : 


Fat  in 
milk 


3.26 


Fat  added 


0.94 


Per  cent  of  fat 
in  enriched  milk 


4.20 


Per  cent  of          Ratio  of  fat 
casein  in  milk         to  casein 

Fat  :  Casein 
2.20  1;  0.52 


It  can,  therefore,  be  seen  that  the  differences  ex- 
isting between  rich  and  poor  milk  are,  so  far  as 
relates  to  the  composition  of  the  cheese  made  from 
them,  such  as  can  be  adjusted  by  removing  fat 


MILK    AND    COMPOSITION    OF    CHEESE 


from  the  rich  milk  or  adding  skim-milk  to  it,  or  by 
adding  fat  to  skim-milk.  The  difference  in  milk 
poor  in  fat  which  makes  the  fat  go  farther  in  mak- 
ing cheese  is  a  difference  which  may  be  character- 
ized, in  a  general  way,  as  a  skim-milk  difference, 
because  it  depends  upon  a  relatively  high  proportion 
of  casein. 

Composition  of  cheese  made  from  milk  contain- 
ing added  cream. — Addition  of  cream  to  normal 
milk  affects  the  cheese  made  from  such  milk  in  a 
way  directly  opposite  to  that  produced  by  skim- 
ming; that  is,  it  increases  the  proportion  of  fat  in 
cheese  in  relation  to  proteins.  A  single  illustration 
will  suffice.  We  give  the  composition  of  cheese 
made  from  normal  milk  containing  4  per  cent  of  fat 
and  also  from  the  same  milk  after  its  fat  content  has 
been  increased  to  6  per  cent  by  the  addition  of 
cream. 


Per  cent 
of  fat 
in  milk 

Pounds  of 
cheese  for 
100  pounds 
of  milk 

Per  cent 
of  fat  in 
cheese 

Per  cent 
of  pro- 
teins 
in  cheese 

Per  cent 
of  cheese  - 
solids  in 
form 
of  fat 

Ratio  of 
fat  to 
proteins 

Normal  milk  .  . 
Enriched  milk 

4.00 
6.00 

10.60 
13.80 

35.  1 
40.4 

22.7 
17.4 

55.7 
64.0 

Fat: 
Proteins 
1:  0.65 
1  :  0.43 

THE  UNITED  STATES  CHEESE  STANDARD 

At  this  point  it  seems  desirable  to  call  attention 
to  the  standard  of  purity  adopted  for  cheese  by  the 
United  States  Department  of  Agriculture  in  con- 
nection with  the  national  pure-food  law.  Its  defi- 
nition of  cheese  made  from  normal  or  whole-milk  is  as 


2j8     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

follows :  "Standard  whole-milk  or  full-cream  cheese 
contains,  in  the  water-free  substance,  not  less  than 
50  per  cent  butter-fat."  There  has  been  wide- 
spread and  needless  misunderstanding  in  regard  to 
the  meaning  of  this  standard.  Many  have  inter- 
preted it  as  meaning  that  normal  or  whole-milk 
cheese  must  contain  50  per  cent  of  fat.  The  law 
does  not  say  that  at  all,  but  that  50  per  cent,  not  of 
the  cheese,  but  of  its  water-free  substance  (cheese- 
solids)  must  consist  of  butter- fat.  This  can  easily 
be  made  clear  by  giving  a  specific  illustration  of 
its  application,  and,  for  this  purpose,  we  take  a  ched- 
dar  cheese  of  average  composition,,  containing: 

Water 36.80  per  cent. 

Water-free  substance  63.20 

Consisting  of  (lOOTOO) 

Fat 33.75 

Proteins.  .  .23.75 

Salts,  etc...  5.70 

63.20 

In  order  to  apply  the  standard  to  any  cheese,  we 
need  to  know  only  the  percentages  of  water  and 
of  fat.  One  then  proceeds  as  follows :  Subtract 
the  percentage  of  water  from  100,  which  gives  the 
cheese-solids  or  water-free  substance,  and  then 
divide  the  percentage  of  fat  in  cheese  by  the  per- 
centage of  water-free  substance.  Expressed  in  out- 
line, the  statement  becomes:  (i)  100  minus  per  cent 
of  water— per  cent  of  water- free  substance;  (2)  per 
cent  .  of  fat-v-per  cent  of  water-free  substance= 
per  cent  of  fat  in  water-free  substance.  Example: 
(i)  100 — 36.80  (per  cent  of  water  in  cheese)= 
63.20  (water-free  substance  in  cheese).  (2)  33.75 
(per  cent  of  fat  in  cheese)-f-63. 20=53.4,  which  is  the 


MILK    AND    COMPOSITION    OF    CHEESE  239 

per  cent  of  fat  in  the  water-free  substance  of  the 
cheese.  In  order  that  a  cheese  be  below  standard, 
the  fat  must  be  less  than  one-half  of  the  water-free 
substance.  In  this  particular  case,  the  cheese  would 
be  belcw  standard  if  the  fat  were  less  than  31.60 
per  cent. 

The  question  naturally  arises  as  to  what  actual 
basis  there  is  for  such  a  specific  standard.  It  is 
based  upon  very  extensive  studies  of  cheese  made 
from  normal  milk.  The  work  of  the  New  York  ex- 
periment station  with  cheese  made  in  New  York 
factories  has  shown  that  the  fat  is  always  more 
than  one-half  of  the  total  solids  or  water-free  sub- 
stance of  cheese.  In  the  case  of  the  lowest  result, 
the  percentage  was  50.39;  the  highest,  56.83;  and 
the  average,  54.  In  very  few  cases  was  the  per- 
centage of  fat  in  cheese-solids  found  below  51.0. 
These  results  are  in  agreement  with  those  obtained 
in  other  states.  For  example,  in  the  Wisconsin 
cheese-scoring  contests  for  April,  May,  June  and  July 
(1908),  results  are  given,  showing  that,  even  in  the 
cheese  poorest  in  fat,  the  fat  was  51.35  per  cent  of 
the  water-free  substance.  The  percentage  of  fat  in 
the  water-free  substance  of  the  cheese  varied  from  this 
figure  to  56.4  as  the  highest. 

In  addition  to  the  results  of  analysis  of  many 
samples  of  cheese  made  from  normal  milk,  the 
composition  of  normal  milk  itself  furnishes  a'  good 
reason  why  the  fat  should  amount  to  more  than 
one-half  of  the  water-free  substance  of  cheese; 
since  a  study  of  normal  milk,  as  it  is  found  at 
cheese-factories  in  New  York  state,  shows  that 
such  milk  does  not  contain  enough  casein,  relative 


240     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

to  fat,  to  make  cheese  of  composition  such  that  its 
water-free  substance  contains  less  than  50  per  cent 
of  fat,  provided,  of  course,  there  is  no  abnormal 
loss  of  fat  in  the  process  of  cheese-making.  For 
example,  it  can  readily  be  seen  from  the  table  on 
p.  234  that  normal  milk  containing  4  per  cent  of 
fat  can  suffer  a  loss  of  nearly  one-fourth  of  its  fat, 
before  the  composition  of  the  cheese  drops  below 
standard.  Normal  milk  containing  3.50  per  cent 
of  fat  can  be  reduced  to  about  3  per  cent  of  fat 
before  the  cheese  made  from  it  contains  less  than 
50  per  cent  of  fat  in  its  water-free  substance. 
Ordinary  milk  containing  3  per  cent  of  fat  could 
have  its  fat  reduced  nearly  to  2.75  per  cent  before 
making  cheese  below  standard.  These  facts  go  to 
show  that  the  United  States  standard  is  well  above 
the  limits  of  danger  for  cheese  properly  made  from 
normal  milk. 

Another  question  in  connection  with  the  cheese 
standard  may  be  asked:  Why  not  use  as  a  standard 
the  percentage  of  fat  in  the  cheese  itself  in- 
stead of  in  the  water- free  substance?  The  present 
standard  has  for  its  purpose,  the  prevention  of  the 
use  of  skimmeti  milk  for  making  cheese  to*  be  sold  as 
normal  or  whole-milk  cheese.  It  does  not  aim  to  con- 
trol the  amount  of  moisture  in  cheese.  If  the 
percentage  of  fat  in  cheese  were  used  as  a  standard, 
then  the  amount  of  water  in  cheese  would  become 
an  important  factor;  because  the  greater  the  mois- 
ture content  of  cheese,  the  less  the  percentage  of  fat 
in  the  case  of  cheese  made  from  milk  of  the  same 
composition.  It  is  recognized  that  different,  markets 
call  for  different  percentages  of  water  in  cheese 


MILK    AND    COMPOSITION    OF    CHEESE  24.! 

and,  by  basing  the  cheese  standard  on  the  water- 
free  substance  of  the  cheese,  this  condition  has  not 
been  interfered  with. 

Some  of  the  state  cheese  standards. — In  some 
states  there  are  laws  which  aim  to  set  up  various 
standards  according  to  the  percentage  of  fat  in 
cheese,  having  one  percentage  of  fat  for  whole-milk 
cheese,  another  for  partial-skim,  another  for  half- 
skim  and  another  for  full-skim.  Such  provisions 
are  cumbersome  in  legal  administration,  as  well 
as  demoralizing  to  the  best  interests  of  the  cheese 
industry  and  deserve  only  severe  condemnation. 

It  is  interesting  to  notice  the  legal  provisions  for 
cheese  standards  which  are  or  have  been  in  force 
in  some  states.  In  California  full-cream  (whole- 
milk)  cheese  must  contain  30  per  cent  of  fat;  half- 
skim  15  per  cent  of  fat;  while  full-skim  cheese  is 
any  cheese  made  from  skim-milk.  Under  these 
provisions  it  would  be  easily  possible  to  make  no 
normal-milk  cheese,  since  all  the  cheese  intended 
to  comply  with  the  requirements  for  so-called  "full- 
cream"  might  be  made  from  partially  skimmed 
milk.  In  Colorado  35  per  cent  of  the  cheese-solids 
(water-free  substances)  must  be  fat.  This  is  15 
per  cent  below  the  United  States  standard.  Under 
such  a  provision  normal  milk  containing  4.0  per 
cent  of  fat  could  have  one-half  of  its  fat  removed 
before  the  cheese  would  drop  below  the  Colorado 
standard  as  given  above.  Under  such  circum- 
stances it  would  be  a  miracle  if  Colorado  had  an 
ounce  of  cheese  made  from  normal  milk  except 
for  the  saving  condition  that  the  actual  relation 
of  such  a  standard  is  probably  not  clearly  under- 
stood by  Colorado  cheese-makers  and  surely  not 


242     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

by  her  legislators,  it  is  to  be  hoped.  In  Minnesota, 
the  law  has  required  that  45  per  cent  of  the 
cheese-solids  be  fat,  which  is  too  low.  In  Missouri, 
the  only  provision  has  seemed  to  be  that  the  cheese 
should  be  made  from  milk  containing  not  less  than 
3  per  cent  of  fat.  In  Ohio,  cheese  containing  less 
than  20  per  cent  of  fat  is  skim-cheese.  This  is 
certainly  a  very  generous  allowance,  since  cheese 
made  from  normal  milk  rarely  contains  less  than 
32  per  cent  of  fat  even  when  green.  It  is  to  be 
hoped  that  the  provisions  in  these  states  for  whole- 
milk  cheese  have  been  or  will  be  changed  to 
conform  with  the  provisions  of  the  United  States 
pure-food  law. 

Misleading  use  of  terms  describing  cheese. — The 
foregoing  discussion  impresses  one  with  the  unfor- 
tunate use  of  certain  words  in  describing  cheese 
made  from  normal  milk  or  whole-milk.  The  ex- 
pressions, "full-cream,"  "factory-cream,"  etc.,  while 
in  common  commercial  use,  and  clearly  understood 
by  those  who  use  them,  are  misleading  to  one  who 
interprets  their  meaning  at  their  face  value.  Ap- 
parently, such  terms  imply  normal  milk  contain- 
ing added  cream.  The  use  of  the  word  cream  in 
any  form  to  describe  normal  milk  is  a  relic  of  the 
inaccurate  knowledge  of  former  generations,  and 
should  be  abandoned  in  the  interests  of  clearness  and 
precision.  Whole-milk  or  normal  milk  is  in  every 
respect  a  much  better  expression  to  use  in  describing 
cheese  made  from  milk  that  is  normal. 


CHAPTER  XX 

The  Composition  of  Cheese  in  Relation 
to  Quality 

In  the  preceding  chapter  it  has  been  demon- 
strated that  cheese  made  from  milk  rich  in  fat 
contains  relatively  and  actually  more  fat  and  less 
proteins  than  cheese  made  from  milk  poor  in  fat. 
Two  such  cheeses,  made  with  equal  skill,  the  milk 
being  uniform  in  every  way  except  in  composition, 
show  a  marked  difference  in  commercial  quality 
(p.  244)  ;  and  the  one  having  the  larger  percentage 
of  fat  would  be  declared  to  be  superior  in  quality. 
This  has  been  demonstrated  in  practical  ways  by 
the  experiment  stations  of  Wisconsin,  Iowa,  Min- 
nesota and  New  York;  and  their  work,  the  first  to 
be  done  along  these  lines,  has  been  supplemented 
and  confirmed  by  the  work  of  others.  It  has  been 
found  generally  true  that  cheese  made  from  milk 
containing  added  cream  is  superior  in  flavor  and  tex- 
ture to  that  made  from  ordinary  normal  milk;  and 
that  made  from  normal  milk  is  superior  in  flavor,  tex- 
ture, body  and  keeping  quality  to  cheese  made  from 
skim-milk. 

Variation  in  quality  in  cheddar  cheese  follows 
more  or  less  closely  the  relation  of  fat  to  proteins 
in  cheese;  the  larger  the  proportion  of  fat,  the  bet- 
ter, in  general,  the  quality  of  cheese  and  the 
higher  the  market  value.  This  fact  is,  of  course, 
associated  with,  and  dependent  upon,  the  function 


244     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

that  milk-fat  performs  in  cheese,  that  of  imparting 
smoothness  of  feeling,  mellowness  of  body,  rich- 
ness and  delicacy  of  taste  and  palatability.  Bear- 
ing on  this  particular  point,  the  late  Henry  E. 
Alvord  makes  the  following  statement  (Yearbook 
of  U.  S.  Dept.  of  Agr.,  1895,  p.  471)  :  "Other  things 
being  equal,  a  cheese  containing  a  large  percentage 
of  fat  is  better,  because,  first,  of  finer  flavor  and 
taste;  second,  of  its  better  consistency;  third,  of  its 
improved  aroma ;  fourth,  of  its  increased  digestibility ; 
fifth,  of  its  more  perfectly  answering  the  requirements 
of  a  complete  food  or  'balanced  ration/ "  In  this 
connection,  it  is  interesting  to  learn  that  in  Germany 
the  custom  of  selling  cheese  according  to  the  per- 
centage of  fat  contained  in  it  is  rapidly  coming  into 
use. 

While  the  view  expressed  above  is  very  generally 
held  and  is  based  upon  experimental  work,  there 
have  been  no  extensive  commercial  opportunities  for 
demonstrating  the  matter  in  a  systematic  way. 
But  some  valuable  facts  bearing  on  this  point  in  a 
most "  direct  and  practical  form  have  just  been 
developed  in  the  four  Wisconsin  cheese-scoring 
contests  held  during  April,  May,  June  and  July, 
(1908).  The  facts  are  all  the  more  interesting  be- 
cause they  are  merely  incidental  to  the  general  pur- 
pose of  these  contests.  The  method  of  conducting 
these  competitive  tests  in  Wisconsin  cannot  be  too 
highly  recommended  to  other  states,  especially  be- 
cause very  full  details  are  given,  unusual  under 
such  circumstances,  making  the  work  of  peculiar 
value  in  enabling  one  to  study  relations  existing 


CHEESE    COMPOSITION    AND    QUALITY 


245 


between  the  composition  of  cheese  and  its  commer- 
cial value.  In  each  of  these  monthly  scorings,  it  is 
significant  that  the  cheese  scoring  highest  contained 
the  largest  amount  of  fat  relative  to  proteins,  while 
the  cheese  scoring  lowest  in  every  case  contained  the 
lowest  amount  of  fat  relative  to  proteins,  as  shown 
by  the  following  data : 


Cheese  scoring  highest 

Cheese  scoring  lowest 

Per  cent 
of  fat 

Per  cent 
of 
proteins 

Ratio  of 
fat  to 
proteins 

Per  cent 
of   fat 

Per  cent 
of 
proteins 

Ratio  of 
fat  to 
proteins 

April  
May  
June  
July  

36. 
35.25 
35. 
35. 

27. 
27.4 
27.5 
29.46 

Fat  rprot'ns 
1:  0.75 
1:  0.78 
1:  0.79 
1:  0.84 

32. 
35. 
34.5 
34.3 

29.2 
29.2 
.29.8 
29.3 

Fat  :  prot'ns 
1:  0.91 
1:  0.83 
1:  0.86 
1:  0.86 

The  most  striking  difference  is  shown  by  the 
April  results,  the  least  by  those  of  July.  In  study- 
ing all  the  available  data,  the  only  apparent  cause 
that  accounts  for  these  differences  is  the  difference 
in  composition.  In  the  case  of  some  of  the  cheeses 
that  were  scored  second  and  third  below  the  high- 
est, as  compared  with  others  that  were  scored  second 
and  third  from  the  lowest,  the  general  relation  of 
quality  and  composition  was  shown  but  not  equally 
in  every  case.  While  these  results  do  not  in  them- 
selves absolutely  prove  the  relation  between  composi- 
tion and  commercial  quality,  their  special  value  is  that 
they  confirm,  in  a  different  way,  the  results  of  other 
work. 

It  cannot  fail  to  be  of  value  in  the  discussion  of 
this  subject  to  present  the  views  of  some  of  those 


246     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

who  have  been  generally  regarded  as  authorities  in 
relation  to  the  commercial  as  well  as  to  the  scientific 
aspects  of  cheese-making.  For  this  purpose,  we 
have  chosen  to  give  the  views  (i)  of  Dr.  Robert- 
son, so  long  Canada's  most  efficient  leader  in  the 
progress  of  all  branches  of  dairying  and  especially 
of  cheese-making,  and  (2)  of  Dr.  Babcock,  who 
has  been  properly  regarded  as  America's  leading 
student  of  dairying  in  its  scientific  relations  and 
who  has  given  special  attention  to  the  question 
under  discussion. 

In  the  Report  of  the  New  York  Dairymen's 
Association  for  1891,  we  find  the  following  state- 
ments in  an  address  given  by  Dr.  Robertson:  "In 
every  case  there  was  a  gradual  reduction  in  the 
quantity  of  cheese  when  there  was  a  less  quantity 
of  butter-fat  in  milk.  .  .  .  However,  this  is 
true  also,  that  the  increased  yield  of  cheese  is  not 
in  direct  proportion  to  the  increased  percentage 
of  butter-fat;  that  is,  milk  containing  3  per  cent 
of  butter-fat  will  yield  a  certain  quantity  of  cheese, 
but  if  you  take  milk  having  one-third  more  fat  (4 
per  cent)  it  will  not  yield  one-third  more  cheese. 
At  the  same  time,  such  milk  is  worth  one-third  more 
for  cheese-making,  and  thereby  hangs  a  tale.  You 
see,  if  it  does  not  yield  so  much  cheese,  it  makes  a 
quality  of  cheese  so  much  better  that  the  market  value 
of  the  cheese  from  TOO  pounds  of  milk  is  a  third 
greater  than  the  market  value  of  the  cheese  in  the 
other  case"  (pp.  198-199).  "Every  two-tenths  of  a 
pound  of  butter-fat  will  improve  the  quality  of  the 
cheese  one-eighth  cent  per  pound,  as  near  as  I  can 


CHEESE    COMPOSITION    AND    QUALITY  247 

find  out.  Thus,  you  have  a  difference  of  about  five- 
eighths  of  a  cent  per  pound  between  cheese  made 
from  3  per  cent  and  4  per  cent  milk"  (p.  201). 

Dr.  Babcock  approaches  the  question  from  quite 
another  point  of  view  (Report  of  New  York  Dairy- 
men's Association  for  1892,  pp.  150,  153,  etc.). 
After  showing  that  fat  is  the  constituent  controlling 
the  value  of  milk,  cream  and  butter,  he  says:  "It  is 
evident  that  the  market  price  of  milk,  of  cream  and  of 
butter  depends  chiefly  upon  the  price  of  butter-fat, 
and  that  other  constituents  have  so  little  influence  that 
they  can  practically  be  neglected. 

"There  is  one  other  important  dairy  product  to  be 
considered,  and  that  is  cheese.  Does  the  same  prin- 
ciple hold  with  this?  I  believe  it  does,  for  on  no 
other  basis  can  I  reconcile  market  prices  all  over  the 
world." 

He  then  goes  on  to  show  by  actual  market  quo- 
tations that  cheese  varies  in  price  according  to 
its  richness  in  fat,  all  the  way  from  n  cents  per 
pound  for  whole-milk,  fancy  cheese  down  to  I  to 
2^2  cents  a  pound  for  full-skim  cheese.  Antici- 
pating some  objections  raised  to  the  method  of 
reasoning  as  applied  to  the  fat  basis  as  a  method 
of  paying  for  milk  at  cheese-factories,  he  con- 
tinues: "I  cannot  leave  this  subject  without  refer- 
ring to  some  of  the  objections  made  to  its  use  in 
cheese-factories.  It  is  urged  that  because  casein 
and  fat  are  intimately  mixed  together  in  cheese, 
they  bring  the  same  price  per  pound  when  sold, 
and  so  should  be  given  the  same  price  in  calculat- 
ing the  value  of  milk  that  is  to  be  used  for  this  pur- 
pose. If  this  is  true,  the  water  which  comprises  a 


248     SCIENCE    AND    PRACTICE    OF    CHEESE- M  AKIXG 

larger  proportion  of  cheese  than  the  casein  should 
be  treated  in  the  same  way,  and  worthless  constit- 
uents in  any  product  should  have  the  same  value 
as  the  mixture  in  which  they  occur.  It  is  absurd, 
on  the  face  of  it,  as  it  gives  entirely  different  values, 
to  the  same  constituent  according  to  the  product 
considered.  It  makes  the  casein,  water  and  fat 
worth  each  about  one  cent  per  pound  in  milk,  the 
same  constituent  worth  30  cents  per  pound  in  but- 
ter and  anywhere  from  I  to  n  cents  per  pound  in 
cheese,  according  to  the  proportions  in  which  they 
are  mixed.  Whereas,  the  relative  value  plan  gives 
consistent  values  in  all. 

"Again,  it  is  said  that  the  life-sustaining  power 
of  a  pound  of  casein  is  about  the  same  as  a  pound 
of  fat,  and  that  they  should  therefore  have  about 
the  same  value;  but  it  must  be  borne  in  mind  that 
the  nutritive  value  and  the  market  value  of  foods  have 
no  relation  to  each  other.  You  can  buy  nutrients 
in  corn  meal  cheaper  than  you  can  in  wheat  flour. 
Maple  sugar  costs  you  two  or  three  times  as  much 
as  beet  sugar,  although  the  two  have  identically 
the  same  effect.  All  of  these  things  are  con- 
trolled by  the  universal  law  of  supply  and  demand, 
and  have  nothing  to  do  with  their  relative  food 
value. 

"When  any  article  has  a  high  value  for  any 
special  purpose,  that  fixes  the  price  which  must 
be  paid  for  it  for  all  other  purposes.  You  cannot 
afford  the  use  of  rosewood  or  mahogany  for  fuel, 
not  because  they  have  less  heat-producing  power 
than  maple  or  birch,  but  because  they  command  a 
higher  price  for  piano  cases  or  other  articles  of 


CHEESE    COMPOSITION    AND    QUALITY  249 

furniture.  The  general  public  esteems  butter-fat  more 
highly  than  casein  and  are  willing  to  pay  a  much 
higher  price  for  it.  It  is  folly  to  stand  in  your  own 
light  and  argue  that  this  is  inconsistent." 

These  arguments  of  Dr.  Babcock  are  based  on 
general  economic  truths  which  hold  good  to-day  as 
fully  as  when  they  were  stated  by  him.  They  are 
facts  which  should  be  kept  in  mind  when  considering 
the  relation  of  composition  of  cheese  to  commercial 
quality  or  market  value.  In  the  I2th  annual  report 
of  the  Wisconsin  experiment  station  (p.  115),  Dr. 
Babcock  also  says : 

"It  is  a  well-established  fact  that  rich  milk  gives 
a  better  quality  of  cheese,  which  commands  a  higher 
price,  than  that  from  poor  milk." 

We  add  also  the  following  quotation  from  an 
address  given  before  the  Wisconsin  cheese-makers' 
convention  at  Milwaukee,  in  1907,  by  Prof.  E.  H. 
Farrington,  dairy  husbandman  at  the  Wisconsin  ex- 
periment station :  "It  will  be  seen  that  the  richer  the 
milk,  the  better  the  price  per  pound  of  cheese 
made  from  it.  I  am  occasionally  asked  if  100 
pounds  of  milk  testing  6  per  cent  of  fat  will  make 
twice  as  much  cheese  as  100  pounds  of  milk  test- 
ing 3  per  cent  of  fat.  The  answer  to  this  question 
is  briefly  that  the  cheese  made  from  the  richer 
milk  is  of  much  better  quality  and  worth  a  higher 
price  per  pound  than  that  made  from  the  thinner 
milk,  and  this  will  help  balance  any  difference  in 
yield.  The  influence  of  the  richness  of  milk  on 
the  quality  of  cheese  is  something  that  should 
not  be  lost  sight  of  in  considering  the  question  of 


25O     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

paying  for  milk  at  a  cheese-factory  by  the  Babcock 
test." 

SKIM-MILK  CHEESE 

The  manufacture  of  skim-milk  cheese  has  been 
fostered  and  protected  in  some  of  our  states.  There 
are  some  considerations  worthy  of  our  attention  in 
connection  with  the  discussion  of  the  composition  of 
cheese  in  relation  to  quality. 

(1)  The    removal    of    fat    from    ordinary   normal 
milk,    such    as    the    mixed    milk    of    our    cheese-fac- 
tories,   results    in    producing    cheese    that    differs    in 
composition   from    whole-milk   cheese.     Such    cheese, 
as  we  have  seen,  contains  less  fat  and  more  casein 
than  that  made  from  normal  milk  having  the  same 
percentage    of    fat.       Skim-milk   cheese   is   an    adul- 
terated food  product,  according  to  the  legal  defini- 
tion of  adulteration. 

(2)  It    is    impossible   to    remove    fat    from    ordi- 
nary   normal    milk    without    affecting    the    composi- 
tion   of    the    cheese    unfavorably,    and    along    with 
this,   the   quality  as   well.     While    skim-milk   cheeses 
may    differ    from    one    another    in    composition    and 
quality,    they   are   all    inferior   to    whole-milk   cheese 
properly  made  from  normal  milk  of  good  quality  in 
all  respects. 

(3)  Skim-milk    cheese    is    not    only    deficient    in 
fat,    but    it    always    contains    an    abnormally    high 
percentage  of  water.       This  is  absolutely  necessary 
in   order  to   make   it   edible   and  have   it   appear  in 
body   and    general    quality   as    a    good    imitation    of 
whole-milk  cheese.       A  skim-milk  cheese  containing 


CHEESE    COMPOSITION    AND    QUALITY  251 

only  the  amount  of  water  held  by  a  whole-milk  cheese 
would  be  practically  unsalable  on  account  of  its 
hardness  and  toughness.  High  percentages  (50-55) 
of  water  are  necessary  in  order  to  make  the  cheese 
appear  to  contain  fat  and  have  a  smooth-feeling 
body. 

(4)  Skim-milk  cheese,  on  account  of  its  high  per- 
centage of  water,  dries  out  very  rapidly  under  ordinary 
conditions  in  the  hands  of  the  consumer  and  becomes 
inedible,  though  it  can  then  be  used  by  experts  in  some 
forms  of  cooking. 

(5)  Skim-milk  cheese,  on  account  of  its  high  per- 
centage of  water  and  of  proteins,   does  not  possess 
the    keeping    qualities    of    whole-milk    cheese.        It 
develops  undesirable  flavors  more  easily  and  does  not 
have  the  same  length  of  life  under  the  same  condi- 
tions,  especially    when   kept   at   temperatures    above 
60°  F. 

(6)  Skim-milk  cheese  generally  becomes  digestible 
less  readily   than   whole-milk   cheese   kept  under  the 
same  conditions ;  and  when  its  proteins  become  rapidly 
soluble,  offensive  flavors  usually  develop,  destroying 
its  value. 

(7)  The  retail  price  of  skim-milk  cheese  is  always 
too    high    in    comparison    with    whole-milk    cheese. 
Separator  skim-milk  cheese  usually  sells  at  retail  for 
10  cents  a  pound,  when  whole-milk  cheese  sells  for  16 
cents.     Such    skim-milk   cheese    sells    for   more   than 
three  times  its  real  value. 

(8)  The   consumer   is  not   really   protected,   even 
when    an   attempt    is    made    by   the    state   to   do    so. 
How  many  people  want  or   even  ask  for  skim- milk 
cheese?      The    average    consumer    is     ignorant    of 


252      SCIENCE   AND    PRACTICE   OF    CHEESE-MAKING 

systems  of  branding  or  other  methods  devised  for  his 
protection.  He  simply  asks  for  cheese  and  takes  what 
is  offered.  It  should  be  made  as  dangerous  for  re- 
tailers to  sell  skim-milk  cheese  for  whole-milk  cheese 
as  it  is  for  them  to  sell  imitation  for  pure  butter. 

(9)  The   indiscriminate  sale  of  skim-milk  cheese 
inevitably  injures  the  sale  of  whole-milk  cheese. 

( 10)  Skim-milk,  consumed  as  such  or  in  the  form 
of  cottage-cheese,  is  a  more  economical  and  nutritious 
food  than  when  used  as  skim-milk  cheese. 

(n)  There  is  a  strong  inclination  on  the  part  of 
those  interested  in  the  cheese  industry  to  believe  that 
the  real  interests  of  dairymen  and  of  the  general  public 
would  be  best  protected  and  promoted  by  the  absolute 
prohibition  of  skim-milk  cheese,  as  demonstrated  by 
Canada. 


CHAPTER  XXI 

Methods  of  Paying  for  Milk  for 
Cheese-Making 

The  subject  relating  to  methods  of  paying  for 
milk  at  cheese-factories  has  been  one  of  more  or 
less  constant  discussion  for  about  twenty  years. 
Shortly  before  the  year  1890,  some  question  was 
raised  as  to  the  fairness  of  paying  for  milk  at 
cheese-factories  by  weight.  Two  factors  worked 
against  the  realization  of  any  practical  results 
coming  from  such  discussion:  (i)  Lack  of  knowl- 
edge regarding  the  relation  of  milk-constituents  to 
yield  and  quality  of  cheese,  and  (2)  the  need  of 
a  practicable  method  for  determining  any  of  the 
cheese-making  constituents  of  milk.  In  1890  Dr. 
Babcock  furnished  his  method  of  determining  fat 
in  milk,  and  then  the  discussion  soon  centered 
about  the  use  of  fat  in  milk  as  a  basis  for  paying 
for  milk  used  in  cheese-making.  The  application 
of  the  test  in  the  case  of  butter-making  was  at 
once  understood  and  utilized ;  but,  in  connection 
with  cheese-making,  it  was  known  that  two  con- 
stituents are  concerned,  fat  and  casein,  and  the 
question  was  therefore  more  complicated  than  in 
the  case  of  butter-making,  where  only  fat  was  con- 
cerned. During  the  years  1891  to  1895,  a  large 
amount  of  investigation  was  carried  on,  which  re- 
sulted in  giving  us  such  a  comprehensive  and  sys- 

253 


254     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

tematic  knowledge  of  the  relations  of  milk  constitu- 
ents to  cheese  as  had  not  been  possible  previously. 
In  general,  it  was  shown  that,  while  the  amount  of 
fat  in  milk  is  not  an  absolute  guide  in  respect  to 
the  yield  of  cheese  from  milks  containing  differ- 
ent amounts  of  fat,  it  is  a  very  much  more  accurate 
index  than  the  mere  weight  of  milk;  and  that, 
while,  in  case  of  milks  containing  higher  percent- 
ages of  fat,  the  yield  of  cheese  is  usually  less  for 
a  pound  of  milk-fat  than  in  the  case  of  milk  con- 
taining lower  percentages  of  fat  (p.  207),  the  cheese 
made  from  the  richer  milk  is  of  more  excellent 
quality  and  has  a  higher  commercial  value  (pp. 
243-249). 

The  fat  basis  began  to  be  introduced  into  actual 
cheese-factory  work  about  1892,  and  its  use  spread 
quite  rapidly  during  the  next  few  years.  This 
method  was  at  first  received  with  considerable  en- 
thusiasm. After  a  few  years  a  reaction  gradually 
took  place  and  the  system  was  abandoned  in  many 
factories,  which  went  back  to  the  old  method  of  pay- 
ing for  milk  by  weight  only.  There  are  several  reasons 
why  the  fat  basis  in  paying  for  milk  for  cheese-mak- 
ing has  experienced  its  ups  and  downs,  like  every 
other  reform  movement,  and  we  will  notice  some  of 
the  most  prominent  of  these. 

(i)  Wherever  the  fat  basis  replaced  the  weight- 
of-milk  method,  the  change  affected  the  dividends  of 
different  patrons  in  different  ways.  Those  furnish- 
ing milk  containing  percentages  of  fat  above  the 
average  received  more  money  for  their  milk,  while 
those  furnishing  milk  containing  percentages  of 


PAYING   FOR    MILK   FOR   CHEESE-MAKING          255 

fat  under  the  average  found  their  dividends  re- 
duced. Therefore,  the  owners  of  cows  giving  milk 
low  in  fat  were  bitterly  disappointed  and  exercised 
their  ingenuity  in  discovering  reasons  why  the  fat 
basis  was  objectionable  and  unfair.  This  attitude 
of  the  producer  of  poor  milk  is,  of  course,  the 
fundamental  reason  why  the  fat  basis  has  been 
abandoned  in  some  cases  where  it  had  been  intro- 
duced. The  other  objections  raised  were  subordinate 
to  this  one,  though  some  of  them  had,  perhaps,  some 
real  basis. 

(2)  The  reliability  of  the  Babcock  test  was 
attacked  and  the  accuracy  of  its  results  called  into 
question.  The  points  of  objection  raised  on  this 
ground  were,  (a)  that  the  Babcock  method  of 
testing  milk  for  fat  is  unreliable  under  all  circum- 
stances; (b)  that,  while  the  method,  when  properly 
handled,  is  accurate,  cheese-makers  are  careless 
or  inefficient  in  operating  the  test,  and  their  results 
are  therefore  inaccurate;  (c)  that  the  glassware 
was  not  always  accurately  graduated  and  conse- 
quently gave  incorrect  results;  (d)  that  cheese- 
makers  deliberately  gave  some  patrons  higher 
results  than  those  indicated  by  the  test.  The  gen- 
eral charge  of  inaccuracy  of  the  test  itself  was, 
of  course,  prompted  by  ignorance  or  malice  or  both. 
There  was  probably  once  some  justification  for  the 
charge  of  carelessness  and  inefficiency  against 
operators  of  the  Babcock  test;  for  it  was  un- 
doubtedly true  to  some  extent  that  cheese-makers 
attempted  to  employ  the  method  who  had  not  been 
properly  instructed  in  its  use  nor  acquired  the 
requisite  accuracy  of  manipulation.  There  was  at 


256     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

one  time  a  strong  disposition  to  over-emphasize 
the  extreme  simplicity  of  the  Babcock  test  and  to 
lose  sight  of  the  fact  that  even  so  simple  a  method 
requires  careful  attention  to  every  detail  and  that 
certain  precautions  must  be  strictly  observed.  It 
was  also  true  that  some  manufacturers  became  care- 
less and  put  on  the  market  glassware  that  was  inac- 
curate. This  difficulty  has  been  effectively  overcome 
in  most  of  the  prominent  dairy  states  by  an  official 
testing  of  all  graduated  glassware  used  in  the  Babcock 
test,  before  it  is  placed  on  sale. 

(3)  Many  cheese-makers  object  to  the  added  work 
involved,    even    when    paid    for    it.      An    unwilling 
cheese-maker  can  easily  influence  patrons  against  the 
method. 

(4)  Another  cause  for  the  discarding  of  the  fat 
basis   in   many   cases   was    the    confusion    introduced 
by  proposing  some  modification  of  the  method  in  the 
interest  of  the  producer  of  poorer  milk,  a  point  which 
we  will  consider  more  fully  later. 

In  the  history  of  the  cheese-making  industry,  we 
can  distinguish  in  the  order  of  their  appearance,  five 
methods  which  have  been  proposed  for  the  purpose 
of  paying  for  milk  at  cheese-factories: 

(1)  Weight  of  milk. 

(2)  Amount  of  fat  in  milk. 

(3)  Relative  values  of  fat  and  other  cheese-solids 
based  on  yield  and  composition  of  cheese. 

(4)  Modification  of  fat  basis  to  include  part  of  the 
milk-casein. 

(5)  Amount  of  fat  and  casein  in  milk. 

We  will  now  consider  each  of  these  methods  as  to 
their  comparative  merits  and  defects. 


PAYING   FOR    MILK    FOR    CHEESE-MAKING          257 

PAYING  FOR  MILK  ON  BASIS  OF  WEIGHT 

Under  this  system  each  patron  receives  the  same 
amount  of  money  for  each  100  pounds  of  milk  de- 
livered at  the  factory.  This  method  possesses  the 
advantage  of  simplicity  and  economy  of  time,  in- 
volving no  additional  work.  Among  the  disadvan- 
tages of  this  method  are  the  following:  (i)  It 
assumes,  as  a  fundamental  basis  of  its  fairness, 
that  all  kinds  of  normal  milk  have  the  same  cheese- 
producing  value;  that,  from  100  pounds  of  any 
milk,  we  make  the  same  amount  of  cheese.  This 
assumption  has  been  abundantly  proved  not  to  be 
true,  since  the  yield  of  cheese  from  100  pounds  of 
milk  may  (p.  207)  vary  all  the  way  from  8  to  13 
pounds  or  more.  The  method  is,  therefore,  unfair 
to  the  producers  of  milk  containing  higher  per- 
centages of  fat.  (2)  This  system  discourages  the 
production  of  milk  of  higher  percentage  in  fat. 
When  weight  alone  is  considered  in  making  pay- 
ment, more  money  can  be  received  by  increasing 
the  amount  of  milk  produced,  without  regard  to 
its  composition ;  and  it  is  thus  found  more  profit- 
able to  produce  milk  as  low  in  fat  as  legal  require- 
ments permit.  (3)  This  system  breeds  criminality, 
because  it  encourages  the  addition  of  water,  re- 
moval of  cream  and  all  similar  forms  of  dishonesty. 
Some  dairymen  have  regarded  the  direct  addition 
of  water  to  milk  as  the  most  economical  way  of 
increasing  milk  production  for  cheese-making  pur- 
poses, but  the  experience  is  not  usually  attended 
with  most  economical  results  for  any  length  of 
time. 


258     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

However  much  difference  of  opinion  there  may 
exist  in  regard  to  the  efficiency  of  different  methods 
of  paying-  for  milk  for  cheese-making,  all  who  are 
in  position  to  give  a  reliable  judgment  in  the  matter 
agree  on  this  one  point,  viz.,  among  the  various 
methods  proposed,  this  one  is  farthest  from  doing 
justice  to  all  producers  of  milk. 

PAYING  FOR  MILK  ON  BASIS  OF  FAT 

When  milk  is  paid  for  on  the  basis  of  its  fat  content, 
each  patron  receives  the  same  amount  of  money  for 
each  pound  of  fat  in  the  milk  delivered.  For  example, 
the  patron  whose  milk  contains  3  per  cent  of  fat 
receives  payment  for  3  pounds  of  fat  for  each  100 
pounds  of  milk  delivered  by  him;  while  the  patron 
whose  milk  contains  4  per  cent  of  fat  receives  pay- 
ment for  4  pounds  of  fat  for  each  100  pounds  of  milk 
furnished  by  him.  The  second  patron  receives  one- 
third  more  per  100  pounds  of  milk  than  the  first  one, 
while,  under  the  weight-of-milk  method,  each  would 
receive  an  equal  sum.  This  can  be  illustrated  as 
follows : 

For  the  sake  of  simplicity,  we  will  compare  the 
milks  furnished  by  two  patrons,  one  milk  con- 
taining 3,  and  the  other  4,  per  cent  of  fat.  We 
will  assume  that  the  cheese  sells  for  10  cents  a 
pound.  We  will  make  the  comparison  on  the  basis 
of  ico  pounds  of  milk,  allowing  that  the  cheese 
yield  from  100  pounds  of  milk  containing  3  per 
cent  of  fat  is  8.30  pounds,  and  from  milk  contain- 
ing 4  per  cent  of  fat,  10.60  pounds,  a  total  of  18.90 
pounds,  bringing  189  cents.  By  the  weight-of-milk 
method,  this  sum  is  divided  equally  between  the 


PAYING   FOR    MILK   FOR   CHEESE-MAKING 


259 


two  patrons,  because  each  furnishes  the  same 
amount  of  milk.  Hence,  each  receives  94.5  cents 
for  the  cheese  made  from  his  milk.  On  this  basis 
the  one  furnishing  milk  containing  3  per  cent  of 
fat  receives  11.4  cents  a  pound  for  each  pound  of 
cheese  made  from  milk  furnished  by  him;  while  the 
other  receives  8.9  cents  for  each  pound  of  cheese  made 
from  his  milk. 

Dividends  based  on  the  percentage  of  fat  in  milk 
are  made  as  follows:  One  patron  furnishes  3 
pounds  of  fat  and  the  other  4.  There  are,  all 
told,  7  pounds  of  fat,  the  cheese  corresponding  to 
which  sells  for  189  cents.  Therefore,  each  pound 
of  fat  is  credited  with  27  cents;  one  patron  re- 
ceives 81  (27X3)  cents  and  the  other,  108  (27X4) 
cents.  In  this  case  the  one  furnishing  the  poorer 
milk  receives  9.76  cents  a  pound  for  the  cheese 
made  from  his  milk,  and  the  other,  10.19  cents.  The 
existing  difference,  0.4  cent  a  pound,  is  generally 
held  to  represent  an  actual  difference  in  the  quality 
and  value  of  the  cheese  (p.  246).  These  results 
can  be  very  well  shown  in  the  following  tabulated 
form: 


Weight-ot-Milk  Method 

Milk-Fat  Basis 

Pounds 
of  fat 
in  100 
pounds 
of  milk 

Pounds 
of  cheese 
made 
from  100 
pounds 
of  milk 

Divi- 
dend 

Money 
rec'd  for 
each 
pound 
of 
cheese 

Money 
rec'd  for 
each 
pound 
of  milk- 
fat 

Divi- 
dend 

Money 
rec'd  for 
each 
pound 
of  cheese 

Money 
rec'd  for 
each 
pound 
of  milk- 
fat 

3 
4 

8.30 
10.60 

Cents 
94.5 
94.5 

Cents 
11.4 
8.9 

31.5 
23.6 

Cents 
81 
108 

Cents 
9.76 
10.19 

Cents 
27 
27 

2OO     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

Of  the  various  objections  deserving  any  atten- 
tion, which  have  not  been  already  noticed,  the  fol- 
lowing are  the  chief  ones  urged  against  this 
method : 

(1)  The  percentage   of  fat  in   milk  is  not  gen- 
erally an  accurate  measure  of  the  amount  of  cheese 
made  from  100  pounds  of  milk.     A  pound  of  fat  in 
milk   containing   3  per   cent   of   fat   represents   more 
cheese  than  does  a  pound  of  fat  in  milk  containing 
4  per  cent  of  fat ;   in  the  former  case,  the  cheese  yield 
is  2.77  pounds  for  one  pound  of  fat  in  milk,  while  in 
the  latter  it  is  2.65  pounds.     On  this  account,  the  milk 
containing  least  fat  does  not  receive  pay  for  all  the 
cheese  it  makes. 

(2)  The  cost  of  making  the  test  is  often  raised  as 
an  objection.       In  actual  practice,  the  difficulty  has 
been  satisfactorily  overcome.       The  usual  custom  is 
to  pay  the  cheese-maker  at  the  rate  of  20  to  25  cents 
a  month  for  each  patron. 

The  principal  reasons  given  for  favoring  the  fat 
basis  are  the  following: 

1 i )  This  method  recognizes  the  fundamental  truth 
that  normal  milks  varying  in  percentage  of  fat  possess 
different  values  for  cheese-making. 

(2)  The  amount  of  fat  in  milk  offers  a  practicable 
and  just  basis   for  determining  the  cheese-producing 
value  of  milk,   when   we  consider  both  quality  and 
quantity  (p.  246). 

(3)  All  temptation  to  adulterate  milk  by  water- 
ing   or    skimming    is    absolutely    removed,    since    a 
man  receives  pay  for  the  number  of  pounds  of  fat 
that  he  furnishes  and  not  merely  for  the  number  of 
pounds  of  liquid  he  carries  to  the  factory.     No  other 


PAYING   FOR    MILK    FOR    CHEESE-MAKING          26l 

method    now    in    use    so    completely    eliminates    the 
temptation  to  adulterate  milk. 

(4)  This   method   promotes   improvement  in  the 
character  of  milk  production.     This  is  not  merely  a 
theoretical  statement,  but  has  been  proved  to  be  true 
in  practice.     It  offers  an  inducement  to  each  dairyman 
to  improve  the  composition  of  his  milk. 

(5)  Improvement  in  the  character  of  dairy  animals 
and  in  the  consequent  yield  and  composition  of  milk 
means  economy  of  production  and  increase  of  profit. 
Cheese-solids  in  rich  milk  can  be  produced  at  less  cost 
than  in  poor  milk. 

(6)  This  method  awakens  interest  in  the  subject 
of  milk  production,   stimulates   a   desire   for   further 
knowledge  and  tends  to  place  the  production  of  milk 
on  a  higher  plane  of  intelligence. 

PAYING  FOR  MILK  ON  THE  BASIS  OF 

YIELD  AND  RELATIVE  VALUE  OF 

CHEESE-SOLIDS 

In  the  twelfth  annual  report  of  the  Wisconsin 
experiment  station  (pp.  114-119),  Dr.  Babcock  has 
worked  out  a  system  of  payment  by  which  the 
yield  of  cheese  and  composition  are  both  taken 
into  consideration.  The  principles  embodied  in 
this  method  have  not  received  the  general  attention 
deserved.  "It  is  not  sufficient  for  a  system  to  give 
the  true  yield  from  each  patron's  milk,  for  this 
makes  skim-milk  cheese  equally  valuable  with  that 
from  the  richest  milk.  The  perfect  system  of 
making  dividends  in  cheese-factories  must  include, 
not  only  the  amount,  but  also  the  relative  values 


262     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


of  fat  and  the  other  cheese-producing  solids;  with 
such  a  system  each  patron  will  receive  his  just  pro- 
portion whether  he  brings  skim-milk,  watered  milk 
or  cream."  His  proposed  method  gives  to  milk- 
fat  a  value  of  6.6,  as  compared  with  a  value  of  i.o 
for  the  cheese-solids  not  fat.  The  following  table 


Per 
cent 
of 

fat 

Lactometer  Degrees 

Per 

cent 
of 
fat 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

2.0 

2.86|   2.88 

2.89     2.91 

2.93 

2.94 

2.96 

2.98    3.00 

3.01 

3.03 

2.0 

21 

2.98j    3.00 

3.01 

3.03 

3.05 

3.06     3.08 

3.10    3.12 

3.13 

3.15 

2.1 

2.2 

3.10,    3.12 

3.13     3.15     3.17 

3.18 

3.2C 

3.22 

3.24 

3.25 

3.27 

2.2 

2,3 

3   ' 

3.24 

3.25     3.27     3.29 

3.30 

3.32 

'    3.34 

3.36 

3.37 

3.39 

2.3 

2.4 

J.34 

3.36 

3.37 

3.39 

3.41 

3.42 

3.44 

3.46 

3.48 

3.49 

3.51 

2.4 

2.* 

3.47 

3.49 

3.50 

3.52     3.53 

3.54 

3.5/i 

3.58 

3.60 

3.61 

3.63 

2.5 

2.6 

3.59 

3.61 

3.62 

3.64     3.65 

3.67 

3.69 

3.71 

3.73 

3.74 

3.76 

2.6 

2.7 

3.71 

3.73 

3.74 

3.76     3.77 

3.79 

3.81 

3.83 

3.85 

3.86 

3.88 

2.7 

2.8 

3.83 

3.85 

3.86 

3.88     3.90 

3.91 

3.93     3.95 

3.97     3.98 

4.00    2.8 

2.9 

3.95     3.97 

3.98 

4.00     4.02 

4.03 

4.05 

4.07 

4.09    4.10 

4.121   2.9 

30 

4.071    4.09 

4.10 

4.12     4.14     4.15 

4.17 

i    4.19 

4.21     4.22 

4.24!    3.0 

3.1 

4.19 

4.21 

4.22 

4.24     4.26j    4.27 

4.29 

4.31 

4.33    4.34 

4.36    3.1 

3.2 

4.31 

4.33 

4.34 

4.361    4.38 

4.39 

4.41 

4.43    4.45     4.46 

4.48    3.2 

3.3 

4.43 

4.45 

4.46 

4.48j    4.50 

4.51 

4.53 

;  4.55 

4.57 

4.58 

4.60    3.3 

3.4 

4.55 

4.57 

4.58 

4.60 

4.62 

4.63 

4.65 

i    4.67 

4.69 

4.71 

4.72     3.4 

3.5 

4.68 

4.70 

4.71 

4.73 

4.75 

4.76 

'  4.78 

4.80 

4.82 

4.83 

4.85     3.5 

3.6 

4.80 

4.82 

4.83 

4.85 

4.87     4.88 

4.90 

4.92 

4.94 

4.95 

4.97    3.6 

3.7 

4.92    4.94 

4.95 

4.97 

4.99     5.00 

5.02 

5.04 

5.06     5.07 

5.09 

3.7 

3.8 

5.041    5.06 

5.07 

5.09 

5.11 

5.12 

5.14 

5.16 

5.18    5.19 

5.21 

3.8 

3.9 

5.16!    5.18 

5.19 

5.21 

5.23 

5.24 

5.26 

5.28 

5.30 

5.31 

5.33 

3.9 

4.0 

5.29    5.31 

5.32 

5.34 

5.36     5.37 

5.39 

5.41 

5.43 

5.44 

5.46 

4.0 

4.1 

5.41 

5.43 

5.44 

5.46 

5.48i    5.49 

5.51 

5.53 

5.55 

5.56 

5.58 

4.1 

4.2 

5.53 

5.55 

5.56 

5.58 

5.60 

5.61 

5.63 

5.65 

5.67 

5.68 

5.70 

4.2 

4.3 

5.65 

5.67 

5.68 

5.70 

5.72 

5.73 

5.75 

5.77 

5.79 

5.80 

5.82    4.3 

4.4 

5.77 

5.79 

5.80 

5.82 

5.84 

5.85 

5.87 

5.89 

5.91 

5.92 

5.941    4.4 

4.5 

5.89 

5.91 

5.92     5.94 

5.96 

5.97 

5.99 

6.01 

6.03 

6.04 

6.06J   4.5 

4.6 

6.02 

6.04 

6.05     6.07 

6.09 

6.10 

6.12 

6.14 

6.16 

6.17 

6.19    4.6 

4.7 

6.14 

6.16 

6.17     6.19 

6.21 

6.22 

6.24 

6.26 

6.28    6.29 

6.31     4.7 

4.8 

6.26 

6.28 

6.29     6.31 

6.33 

6.34 

6.36 

6.38 

6.40'    6.41 

6.43    4.8 

4.9 

6.38 

6.40 

6.41     6.43 

6.45 

6.46 

6.48 

6.50 

6.52    6.53 

6.55i   49 

5.0 

6.50 

6.52 

6.53     6.55 

6.57 

6.58 

6.60|    6.62 

6.64    6.65 

6.67|    5.0 

5.1 

6.62 

6.64 

6.65     6.67 

6.69 

6.70 

6.72 

6.74 

6.76    6.77 

6.79    5.1 

5.2 

6.74 

6.76 

6.77     6.79 

6.81 

6.82 

6.84 

6.86 

6.88    6.89 

6.91J    5.2 

5.3 

6.86 

6.88 

6.89     6.91 

6.93 

6.94 

6.96 

6.98 

7.00    7.01 

7.03    5.3 

5.4 

6.98 

7.00 

7.01     7.03 

7.05 

7.06 

7.08 

7.101    7.12     7.13 

7.15!    5.4 

5.5 

7.10 

7.12 

7.13 

7.15 

7.17 

7.18 

7  />0 

7.22!    7.24'    7.25 

7.27!    5.5 

5.6 

7.23 

7.25 

7.26 

7.28 

7.30 

7.31 

7  31 

7.35|    7.37     7.38 

.7.40    5.6 

5.7 

7.35 

7.37 

7.38 

7.40 

7.42 

7.43 

7.45 

7.47     7.49     7.50 

7.52J    5.7 

5.8 

7.47 

7.49 

7.50 

7.52 

7.54 

7.55 

7.57 

7.59    7.61     7.62 

7.64    5.8 

5.9 
6.0 

7.59 
7.71 

7.61 
7.73 

7.62 
7.74 

7.64 
7.76 

7.66 
7.78 

7.67 
7.79 

7.69 
7.81 

7.71 
7.83 

7.73 
7.85 

7.74    7.76! 
7.86    7.88 

5.9 
6.0 

PAYING  FOR  MILK  FOR  CHEESE-MAKING  263 

is  worked  out,  based  on  yield  of  cheese  and  relative 
value  of  cheese-solids  for  milks  containing  different 
percentages  of  fat  from  2  to  6.  Values  are  given  which 
can  be  used  directly  in  the  same  manner  as  the  per- 
centages of  fat  are  used  in  case  of  the  fat  basis. 
These  values  appear  to  be  quite  accurate,  especially 
for  milks  containing  3.5  to  4.0  per  cent  of  fat. 
The  only  additional  labor  required  is  to  apply  the 
lactometer  to  a  sample  of  each  milk  and  take  the 
reading.  "This  modification  would  give  to  each 
patron  the  same  amount  of  money  which  he  would 
obtain  if  his  milk  were  manufactured  by  itself.  In 
this  respect  it  differs  widely  from  those  modifica- 
tions of  the  relative-value  plan  which  aim  to  make 
dividends  in  proportion  to  the  pounds  of  cheese 
which  each  milk  will  produce,  leaving  out  entirely 
the  quality  of  the  cheese."  The  following  illustration 
shows  the  application  of  this  method : 

One  patron  furnishes  milk  showi-ng  by  test  3 
per  cent  of  fat  and  a  lactometer  (Quevenne)  read- 
ing of  28;  another,  milk  with  4  per  cent  of  fat  and 
a  lactometer  reading  of  34.  Turning  to  the  preced- 
ing table,  it  is  found  that  milks  corresponding  to 
these  percentages  of  fat  and  lactometer  readings 
have  relative  values  for  cheese-making  represented 
by  the  numbers  4.10  and  5.43.  To  find  the  dividend 
of  each,  we  divide  the  amount  of  money  (189  cents) 
received,  by  the  sum  (9.53)  of  these  two  num- 
bers, which  gives  19.83.  This  number  multiplied  by 
4.10  and  5.43  gives  the  respective  dividends  of  the 
two  patrons. 


264     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


Pounds  of 

Pounds  of 

Money  rec'd 

Money  rec'd 

fat  in 

cheese  made 

for  each 

for  each 

100  pounds 
of  milk 

from  100 
pounds  of  milk 

Dividend 

pound  of 
cheese 

pound  of 
milk-fat 

Cents 

Cents 

3 

8.30 

81.3 

9.80 

27.10 

4 

10.60 

107.7 

10.16 

26.92 

By  comparing  these  results  with  those  given  by  the 
simple  fat  basis  (p.  259),  and  other  methods,  we  see 
that  the  values  are  much  closer  to  the  results  of  the 
fat  basis  than  by  any  other  method. 

Application  of  principle  to  fat  and  casein. — This 
same  principle  could  be  readily  applied  when  we 
know  the  percentages  of  fat  and  of  casein  in  milk. 
We  might  be  even  more  liberal  and,  instead  of  al- 
lowing only  one-sixth  for  casein,  allow  as  much 
as  one-fourth.  In  this  case,  the  dividends  would 
be  based  on  the  fat  plus  one-fourth  of  the  casein 
in  each  case.  This  is  illustrated  in  connection  with 
the  fat  and  casein  method  of  making  dividends  (p. 
270). 

MODIFICATION  OF  FAT  BASIS  KNOWN  AS 
THE  "FAT-PLUS-TWO"  METHOD 

By  this  method  the  percentage  of  fat  in  milk  is 
increased  by  2  and  the  results  used  as  in  making 
dividends  on  the  fat  basis.  The  method  originated 
in  Canada.  The  first  suggestion  was  made  about 
1893,  when  at  one  of  the  cheese-factories  the  plan 
was  adopted  of  adding  I  to  the  fat  in  making  divi- 
dends, because  it  was  noticed  that  this  method 
more  closely  approximated  the  cheese  yield  than 


PAYING    FOR    MILK    FOR    CHEESE-MAKING 


the  use  of  fat  alone.  This  method  was  made  a  sub- 
ject of  study  at  the  Ontario  Agricultural  College  and 
was  modified  by  adding  2  to  the  fat  in  making 
dividends. 

The  dividends  are  made  in  the  following  manner 
under  this  method,  using  the  illustration  already 
given  (p.  258)  for  milks  containing  3  and  4  per  cent 
of  fat.  The  receipts  from  sale  of  cheese  are  189  cents. 
Instead  of  one  patron  receiving  three-sevenths  and  the 
other  four-sevenths  of  this  amount,  one  receives 
five-elevenths  and  the  other  six-elevenths,  as  shown 
thus  : 

3+2=5 
4+2=6 


ii 


The  results,  compared  with  those  of  the  fat  basis, 
are  as  follows  for  this  particular  illustration : 


Fat-Basis  method 

Fat-plus-2  method 

•p        _. 

Pounds 
of  fat 
in  100 
pounds 
of  milk 

of  cheese 
made 
from   100 
pounds 
of  milk 

Divi- 
dend 

Money 
received 
for  each 
pound 

Money 
received 
for  each 
pound 

Divi- 
dend 

Money 
received 
for  each 
pound 

Money 
received 
for  each 
pound 

of 

of 

of 

of 

cheese 

milk-fat 

cheese 

milk-fat 

Cents 

Cents 

Cents 

Cents 

3 

8.30 

81 

9.76 

27 

86 

10.36 

28.7 

4 

10.60 

108 

10.19 

27 

103 

9.72 

25.7 

This  method  is  based  on  an  attempt  to  approxi- 
mate yield  of  cheese  as  a  basis  to  use  in  paying 
for  milk.  It  is  supposed  that  the  addition  of  2  to 


266     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

the  per  cent  of  fat  makes  allowance  for  the  casein 
of  the  milk,  and,  therefore,  that  milks  which  are 
low  in  fat  will  get  such  a  proportion  of  casein  as 
will  balance  the  difference  existing  between  milk 
poor  in  fat  and  milk  rich  in  fat  in  respect  to  yield 
of  cheese  per  pound  of  fat;  and  that,  therefore, 
taking  the  casein  into  consideration  along  with  the 
fat  will  give  us  a  more  accurate  relation  in  regard 
to  yield  of  cheese  and  percentage  of  fat  in  milk. 
This  ought  to  be  true  and  is  true  to  a  certain  degree. 
So  far  as  we  do  take  casein  into  consideration,  we 
get  just  that  much  nearer  to  the  average  of  cheese 
yield,  speaking  of  yield  alone  and  not  considering 
quality. 

The  objections  which  have  been  brought  against  this 
method  are  the  following: 

(1)  It    does    not    recognize    any    casein    in    milk 
above  2   per  cent;    it   would  be   a   fair  measure  of 
yield  of  cheese  if  all  milks  contained  2  per  cent  of 
casein,   no   more    and    no    less.     This    is,    of   course, 
not  in  accordance  with  the  actual  facts.     The  addi- 
tional amount  of  casein  above  2  per  cent,  which  is 
usually  found  in  richer  milks,   is  wholly  ignored  by 
this  method.     For  example,  under  this  method,  milk 
containing  4  per  cent  of  fat  would,  after  adding  2, 
be  given  a  value  of  6,  whereas  it  should  be  given  a 
value  of  6.4  or  6.5  or  more  on  the  basis  of  its  usual 
casein  content. 

(2)  This  method  is,  therefore,  in  the  interest  of 
milk    low    in    fat.     It    gives    undue    advantage    to 
poorer  milk,  and,  to  the  same  extent,  works  against 
the  producer  of  richer  milk.     It  has  been  generally 
held  that  too  much  encouragement  cannot  be  given 


PAYING   FOR    MILK    FOR    CHEESE-MAKING          267 

to  farmers  to  produce  milk  of  richer  composition. 
In  the  illustration  given  above,  one  fails  to  see  the 
justice  of  a  method  which  gives  to  the  producer  of 
poorer  milk  10.36  cents  a  pound  for  his  cheese  and 
to  the  producer  of  richer  milk,  only  9.72  cents  a 
pound  for  cheese  that  is  better  if  the  milk  is  made 
into  cheese  by  itself. 

(3)  This  method  offers  a  premium  on  watering 
milk,   because  the  percentage  of  fat  in   milk    (high 
or  low)   is  credited  with  only  2  per  cent  of  casein; 
and,    hence,    the    lower    the    percentage    of    fat,    the 
larger    will    be    the    relative    amount    of    casein    and 
the  greater  the  price  received  for  each  pound  of  fat. 
For   example,   a  patron   furnishing  milk  with  4  per 
cent  of   fat   could  add,   say,  33   pounds  of  water  to 
loo  pounds  of  milk,    thus    reducing    the    percentage 
of  fat  to   3.       He    would    then    have   the   benefit   of 
the  added  factor  for  133  pounds  of  milk  instead  of 
100  pounds.     He  would  thereby  increase  his  dividend 
from  103  to  108  cents. 

(4)  This    method    also    offers    a    premium    on 
skimming  as  well  as  watering  milk.     This  can  best 
be    made    clear    by    illustration.        A    patron     who 
furnishes   milk   containing  4   per   cent   of   fat   skims 
it   so   as   to   make    it   contain   3    per   cent   and   then 
adds    enough    water    to    make    the    weight    of    milk 
loo    pounds    again.       The    cheese    made    from    100 
pounds   of   such    milk   would   be    about   8.9    pounds. 
The   milk   of   the   other  patron,   who    furnishes   100 
pounds  of  normal  milk  containing  3  pounds  of  fat, 
makes  8.3  pounds  of  cheese,  a  total  of  17.2  pounds 
for  the  200  pounds  of  mixed  milk.     This,  we  assume, 
sells   for    172   cents   and   is    evenly   divided  between 


268     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

the  two  patrons,  because  each  furnishes  milk  con- 
taining 3  per  cent  of  fat.  Each,  therefore,  receives 
86  cents.  If  the  patron  who  produces  milk  with  4 
per  cent  of  fat  takes  the  normal  milk  to  the  factory, 
he  receives  on  the  "fat-plus-two"  basis  103  cents,  as 
we  have  already  seen.  If  he  skims  his  milk  as  de- 
scribed above,  he  receives  86  cents,  or  17  cents  less; 
but  he  has,  as  an  offset  to  this,  one  pound  of  milk-fat 
which  he  can  sell  for  25  cents  to  30  cents.  There- 
fore, he  is  the  gainer  by  all  that  he  can  get  for  his 
pound  of  milk-fat  over  17  cents. 

(5)  This  method,  in  opposition  to  the  teachings  of 
Robertson,  Babcock  and  many  others,  wholly  ignores 
the  fact  that  composition  and  quality  vary  with  fat 
in  milk  and  that  cheese  made  from  richer  milk  is  of 
higher  value. 

While  these  objections  hold  good,  still  the  "fat- 
plus-two"  method  is  unquestionably  a  great  ad- 
vance over  the  old  weight-of-milk  method.  The 
most  unfortunate  feature  about  this  method  is  the 
confusion  which  its  introduction  has  caused  among 
dairymen.  Instead  of  regarding  it  as  a  modifica- 
tion of  the  fat  basis,  dairymen  have,  in  many  cases, 
thought  that  the  whole  principle  of  paying  for  milk 
by  any  other  method  than  the  weight-of-milk 
system  was  under  suspicion.  Dairymen  do  not 
yet  understand  the  details  of  different  methods 
clearly  enough  to  discriminate,  and,  when  they 
are  told  that  the  fat  basis  is  unreliable  and  in- 
accurate, they  most  naturally  lose  confidence  in 
all  methods  based  on  the  fat-test  and  go  back  to 
the  weight-of-milk  system.  Those  who  produce 
poor  milk  take  advantage  of  such  an  opportunity 


PAYING   FOR    MILK    FOR    CHEESE-MAKING          269 

to  upset  the  entire  system  based  on  the  fat-test. 
Thus,  the  whole  situation  has  been  needlessly  con- 
fused, rather  than  benefited,  for  the  average  cheese- 
factory  patron. 

PAYING  FOR  MILK  ON  BASIS  OF  FAT  AND 
CASEIN 

By  this  method  the  percentages  of  fat  and  casein 
in  each  patron's  milk  are  added  and  the  figures 
thus  obtained  are  used  in  apportioning  dividends, 
as  in  the  fat  basis.  This  can  be  illustrated  as  fol- 
lows: 

We  will  make  use  of  the  figures  already 
employed  in  illustrating  the  other  methods.  One 
patron  furnishes  milk  containing  3  per  cent  of  fat 
and  2.1  per  cent  of  casein;  the  other,  milk  with 
4  per  cent  of  fat  and  2.5  per  cent  of  casein.  Each 
furnishes  100  pounds  of  milk;  the  total  amount  of 
cheese  made  is  18.9  pounds,  realizing  189  cents. 
We  add  together  the  amounts  of  fat  and  casein  in 
the  two  milks,  obtaining  n.6  as  the  total  number 
of  pounds  of  fat  and  casein  in  the  200  pounds  of 
milk.  The  total  amount  of  money  received  for  the 
cheese  is  divided  by  the  total  amount  of  casein  and 
fat,  which  gives  us  16.3  cents  as  the  value  of  each 
pound  of  mixed  fat  and  casein  in  milk.  The  divi- 
dend of  the  patron  furnishing  the  poorer  milk  is 
16.3X5.1,  which  equals  83  cents;  the  dividend  of 
the  other  is  16.3X6.5,  which  equals  106  cents.  In 
this  case,  each  receives  the  same  price  for  the 
cheese,  10  cents  a  pound,  but  not  the  same  for  milk- 
fat;  the  poorer  milk  receives  27.7  cents  a  pound 


2/0     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


lor  its  fat;  the  richer  milk,  26.5  cents.  Below  are 
given  in  tabulated  form  the  results  of  this  and  other 
methods  already  considered,  and  also  the  modification 
of  the  fat-and-casein  basis,  in  accordance  with  the 
relative- value  suggestions  of  Dr.  Babcock ;  that  is,  we 
allow  full  value  for  fat  and  one-fourth  value  for 
casein  (p.  264). 


Per  cent 
of  fat 
in 
milk 

Per  cent 
ot 
casern 
in  milk 

Pounds 
of 
cheese 

Divi- 
dend by 
fat  and 
casein 

Divi- 
dend by 
fat 
method 

Dividend 
by  fat  and 
one-fourth 
casein 
(P.  264) 

Dividend 
by  "fat+2" 
method 

Cents 

Cents 

Cents 

Cents 

3 

2.1 

8.30 

83 

81 

82 

86 

4 

2.5 

10.60 

106 

108 

107 

103 

The   fat-and-casein  method  has  the   following  ad- 
vantages : 

1 i )  It  is  an  accurate  measure  of  the  yield  of  cheese 
in  the  case  of  all  kinds  of  milk  when  the  losses  of  milk 
constituents  are  not  excessive. 

(2)  The  temptation  to  adulterate  by  watering  is 
entirely  removed. 

The  following  disadvantages  suggest  themselves: 

(1)  Assuming  that  a  test  for  casein  gives  results 
as  accurate  as  the  Babcock  test  for  fat  in  the  hands 
of  ordinary  cheese-makers,  it  is  objected  that  the  test 
involves  extra  labor  on  the  part  of  the  cheese-maker, 
for  which  he  cannot  well  afford  the  time.     The  same 
objection  is  often  made  against  the  Babcock  test,  and 
it  would,  of  course,  be  much  more  forceful  in  regard 
to  a  casein-test. 

(2)  An     extra     test     involves     additional     cost, 
even    in    case    a    cheese-maker    could    find    time    to 


PAYING    FOR    MILK    FOR    CHEESE-MAKING          271 

make  both  fat  and  casein  tests.  If  a  cheese-maker 
were  paid  on  tJhe  basis  of  what  is  received  for 
making  fat-tests,  it  would  amount  to  $50  or  $60  a 
season  for  most  cheese-factories.  To  this  must  be 
added  cost  of  materials  and  breakage  of  glassware, 
which  might  be  conservatively  placed  at  $10  to  $15. 
There  would  thus  be  a  total  outlay  on  the  part  of  the 
patrons  amounting  to  $60  to  $75  for  the  season  in 
having  the  casein-test  made. 

(3)  The   fat-and-casein   method   does   not   recog- 
nize   any    difference    in    the    value    of    cheese    made 
from  milk  high   and   low   in  percentage   of   fat.      It 
places   the   market   value    of   casein    on   an   absolute 
level   with   milk-fat,   while   Dr.   Babcock  gives   milk- 
fat  in  cheese  a   value  6.6  times   that  of  casein    (p. 
262). 

(4)  The  use  of  the  fat-and-casein  method  offers 
a   temptation   to    remove    fat    from   milk    or   to    add 
skim-milk,   in   case   of   milk   to   be   used    for   cheese- 
making.       To    illustrate,   casein    in   skim-milk   has   a 
market  value   for  the   dairyman  not  to   exceed  2   or 
3   cents  a   pound,   while  milk-fat  is   worth  about  30 
cents    a    pound.       In    good    cheese,    casein    and    fat 
together  bring  about   18  cents  a  pound.       If  casein 
is  paid  for  on  a  par  with  fat,  then  by  adding  skim- 
milk  to  normal  milk,  one  can  increase  the  price  of 
his   skim-nrilk  casein  about  nine  times.       The   same 
would  be  true   if  fat  were   removed  from   milk  and 
sold  as  butter  or  cream.       In  whatever  manner  one 
increases   the   ratio   of  casein   to   fat  in   milk,  he  in- 
creases the  dividend  value  of  casein  in  cheese-making, 
when  fat  amir  casein  are  treated  as  of  equal  value  in 
making  dividends. 


272     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

(5)  The  fat-and-casein  method  requires  more  time 
in  calculating  dividends. 

(6)  Some   have   expressed   the    fear    that,   under 
this    system,    the    increased    value    of    casein    would 
lead  dairymen  to  breed  cows  for  milk  high  in  casein, 
and   that   this    would   result   in   a   poorer   quality   of 
cheese  and  general  consequent  danger  to  the  cheese 
industry.     In  fact,  the  use  of  cows  giving  milk  with 
a   high   casein   content   has   been    specifically   empha- 
sized by  some   as  a  desirable   end  to  work   for  and 
it  is  urged  that  such  an   aim  would   be   realized  by 
the    recognition    of    casein    in    cheese-making    as    of 
equal  value  with  fat.       Assuming  that  the  percent- 
age of  casein  in  milk  could  be  notably  increased  in 
an   economical    manner,   what   would   be   the   result? 
By    referring   to    pages    231-237,    it    can    readily    be 
seen    that    the    process   would    be    nothing    more    or 
less   than   a   system   of   adding   skim-milk   to   normal 
milk,    thereby    increasing    the    amount    of    casein    in 
milk    relative    to    fat.       This    fact    is    probably    not 
fully  appreciated   by   those   who   are   advocating  the 
process.     We    have    probably    reached    the    limits    of 
safety,  in  more  than  one  sense,  in  many  strains   of 
Holsteins    and    Ayrshires,    as    regards    the    high    re- 
lation of  casein  to   fat.      We  do  not  need  to  spend 
time   and    energy    to    breed    cows    for    milk    in    the 
direction    of  skim-milk    for    cheese-making.       Some 
progressive     dairymen    are,     happily,     still     so    old- 
fashioned  in  their  ideas  as  to  advocate  the  opposite 
process,    viz.,    increasing   the   yield    of    fat    in    milk 
without  paying  any  attention   to   its   skim-milk  con- 
stituent,   casein.       This    is    simply    raising    the    old 
question  that  used  to  be  discussed  so  much  20  years 


PAYING   FOR    MILK   FOR   CHEESE-MAKING          273 

and  more  ago  regarding  the  "butter  cow"  and  the 
"cheese  cow."  Thus,  in  the  1892  report  of  the 
Vermont  experiment  station  (pp.  122,  123),  this  whole 
question  is  ably  discussed,  the  article  closing  as 
follows:  "The  logical  conclusion,  then,  is  that  the 
so-called  'cheese  cow/  that  is,  the  cow  which  is 
especially  good  for  cheese  rather  than  for  butter, 
does  not  exist,  and  that  whenever  a  cow  is  found 
that  is  good  for  cheese-making  purposes,  the  milk 
of  that  cow  is  equally  good  for  the  manufacture  of 
butter."  The  following  statement  is  found  on  page 
471  of  the  1895  yearbook  of  the  United  States  De- 
partment of  Agriculture,  in  an  article  by  the  late 
Henry  E.  Alvord:  "Cumulative  evidence  is  un- 
necessary. These  important  truths  are  established, 
namely:  The  best  milk  makes  the  best  cheese,  and 
the  most  of  it;  the  milk  which  is  most  profitable 
for  butter  is  also  the  most  profitable  for  cheese; 
the  best  butter  cow  is  the  best  cheese  cow."  In  a 
discussion  of  the  same  subject,  Bulletin  No.  9  of 
the  New  Hampshire  station  contains  the  following 
statements:  "We  are  told  that  cows  which  are 
giving  milk  poor  in  fat  and  are  therefore  poor  but- 
ter cows  are  great  cheese  cows.  ...  A  milk 
rich  in  fat  is  not  only  a  good  milk  for  butter  but 
also  a  good  milk  for  cheese,  while  the  reverse  is  also 
true." 

In  harmony  with  the  general  tenor  of  the  pre- 
ceding statements,  the  investigation  carried  on  with 
different  breeds  of  cows  at  the  New  York  experi- 
ment station  appears  to  demonstrate  clearly  that  a 
pound  of  cheese-solids  can  be  produced  at  less 


274     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

cost  in  case  of  milk  rich  in  fat  than  in  case  of  milk 
poor  in  fat. 

(7)  Another  highly  important  question  has 
been  raised  in  connection  with  the  use  of  a  casein- 
test  in  paying  for  milk  at  cheese-factories — Is  it 
worth  the  time  and  trouble  expended  on  it?  It 
is  not  worth  the  time,  if,  with  Dr.  Robertson,  Dr. 
Babcock  and  others,  we  believe  that  casein  is  not 
equal  in  value  to  fat  for  cheese  production  in  rela- 
tion to  composition  and  quality  of  cheese.  If,  on 
the  other  hand,  we  believe  that  yield  of  cheese 
alone  should  be  considered  and  that  fat  and  casein 
are  of  equal  value,  pound  for  pound,  in  cheese  pro- 
duction, even  then  we  can  ask  the  question — Are 
the  differences  caused  by  variation  in  casein  worth 
the  trouble  and  expense  involved  in  making  a 
casein-test  in  addition  to  fat?  To  what  extent 
will  dividends  be  readjusted  among  patrons  and 
in  what  manner?  While  this  question  can  not 
be  answered  finally  until  results  have  been  secured 
in  numerous  factories,  we  have  sufficient  data  on 
hand  to  give  a  definite  answer  in  the  case  of  one 
representative  New  York  factory  for  one  season. 
We  have  fat  and  casein  determinations  during  one 
factory  season  for  each  of  50  different  herds  of 
cows  whose  milk  was  taken  to  one  cheese-factory. 
The  analyses  of  milk  were  made  every  other  week 
for  each  herd  separately  from  May  to  October  in- 
clusive. In  23  cases,  the  fat-and-casein  method 
gave  a  larger  dividend  than  did  the  fat  alone  by 
an  average  of  1.6  cents  for  each  100  pounds  of  milk, 
the  greatest  difference  in  the  case  of  any  one  patron 
being  5.9  cents,  and  the  least  o.i  cent.  In  one 


PAYING  FOR   MILK   FOR  CHEESE-MAKING  2J5 

case,  both  methods  gave  the  same  result.  In  26  cases, 
the  fat  method  gave  higher  results  by  an  average 
of  1.4  cents  for  100  pounds  of  milk,  the  difference 
varying  in  the  case  of  different  individuals  from  5.1 
cents  to  o.i  cent. 

The  greatest  difference  found  in  favor  of  the 
fat  and  casein  basis,  5.9  cents  per  100  pounds  of 
milk,  would  mean  for  an  entire  factory  season 
nearly  $20,  assuming  that  this  patron  furnished 
33,600  pounds  of  milk,  an  average  of  224  pounds 
for  150  days,  which  was  the  actual  average  for 
each  patron.  Summarizing  the  results  on  this  basis, 
we  have  23  men  receiving  more  money  by  the  fat- 
and-casein  method,  amounting  altogether,  for  the 
season,  to  $123.46,  the  increased  dividends  of  each 
varying  from  33.6  cents  to  $19.83,  and  averaging 
$5.39.  As  a  matter  of  fact,  about  two- thirds  of  the 
money  would  go  to  8  patrons.  One  patron  re- 
ceives the  same  amount  either  way.  The  remain- 
ing 26  patrons  receive  less  by  the  fat-and-casein 
method  than  by  the  fat  basis,  amounting  altogether 
to  $123.46,  varying  from  33.6  cents  to  $17.13,  and 
averaging  $4.75  each. 

On  the  basis  of  the  estimated  cost  of  $60  to  $75 
spent  in  paying  for  the  test,  more  than  half  of  the 
difference  ($123.46)  would  be  used  up,  so  that,  if 
those  who  benefited  by  the  casein-test  paid  for  it, 
there  would  be  distributed  not  more  than  half  of 
the  amount  above  given.  This  would  mean  an  ex- 
penditure of  $60  to  $75,  in  order  to  adjust  a  dif- 
ference of  $123  in  the  interest  of  23  men  who  fur- 
nish milk  which  tests  below  the  average  in  fat. 
The  entire  sum  involved  amounts  to  less  than  0.4 


2^6     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

per  cent  of  the  factory's  receipts  from  cheese. 
Under  such  circumstances,  it  is  not  at  all  likely 
that  the  27  patrons  would  vote  to  employ  the  fat- 
and-casein  method  in  distributing  dividends,  nor  is 
it  likely  that  most  of  the  23  men  benefited  would 
ask  it,  when  the  high  relative  cost  of  making  a 
redistribution  was  understood.  While  the  results 
represent  only  one  cheese-factory,  the  conditions 
are  typical  of  those  prevailing  in  New  York  state, 
and  results  that  are  strikingly  different  from  these 
would  probably  be  exceptional.  If  the  dividends 
were  made  on  the  basis  of  allowing  less  for  casein 
than  fat,  as  recommended  by  Dr.  Babcock  (p.  264), 
the  difference  in  favor  of  the  patrons  furnishing 
extra  casein  would  be  less  than  one-quarter  what 
they  are  when  we  allow  the  same  price  for  casein 
as  for  fat.  On  such  a  basis,  the  difference  would 
be  only  about  half  the  cost  of  making  the  casein- 
tests. 

PAYMENT  ON  BASIS  OF  FAT  AND  CAL- 
CULATED CASEIN 

In  view  of  the  fact  that  so  many  cheese-fac- 
tories are  still  paying  for  milk  on  the  basis  of 
weight  alone,  as  a  result  of  the  confusion  that  has 
been  created  in  regard  to  the  fairness  of  the  fat 
basis,  a  method  might  be  suggested  which  would 
find  use  in  factories  that  are  now  using  no  test 
system,  which  would  be  far  superior  to  the  weight- 
of-milk  method  and  at  the  same  time  possess  certain 
advantages  over  other  modifications  of  the  fat 
basis.  Such  a  method  would  be  to  pay  on  the  basis 


PAYING   FOR    MILK   FOR   CHEESE-MAKING          277 

of  the  fat  and  of  the  casein  calculated  according  to 
the  formula,  (Fat — 3)Xo.4+2.i.  Such  a  method 
is  not  recommended  where  the  fat  basis  is  being 
used,  but  only  as  a  compromise  where  it  comes  to 
a  choice  between  some  such  basis  and  the  weight- 
of-milk  method;  in  other  words,  where  the  preju- 
dice against  the  fat  basis  is  too  strong  to  be  over- 
come. The  amount  of  casein  obtained  thus  is 
added  to  the  fat  and  the  dividends  calculated  in  the 
manner  given  on  p.  284.  The  use  of  a  method 
basing  dividends  on  the  fat-test  and  the  amount  of 
calculated  casein  would  possess  the  following  ad- 
vantages : 

(1)  It  would  be  preferable  to  the  fat-and-casein 
method,  which  requires  two  separate  tests  to  be  made, 
since  no  test  would  be  needed   for  casein,  but  only 
for  fat.       It  would,  therefore,  involve  no  additional 
expense  of  time,  labor  or  money,  as  is  the  case  with 
the  casein-test. 

(2)  It   would  be   more   fair   than   the   "fat-plus- 
two"   method,    because    milk   containing   higher   per- 
centages  of   fat   would   receive   payment   for   the   in- 
creased    amount    of     casein     that    goes     with    that 
increased    percentage    of    fat,    instead    of    receiving 
credit  for  only  2  per  cent  of  casein,   rich  and  poor 
milks  alike.       This  method  gives  results  that  are  in 
most  cases  much  closer  to  the  yield  of  cheese  than 
the  "fat-plus-two"  method. 

(3)  The  watering  or  skimming  of  milk  could  not 
affect  the  results,  because  the  casein  is  made  to  depend 
on   the   fat   content.     In   this   respect   the  method   is 
much  superior  to  the  fat-and-casein  'or  the  fat-plus- 
two  method. 


278     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


(4)  No  more  labor  need  be  involved  than  in 
the  case  of  the  fat  basis,  either  in  the  matter  of 
testing  or  in  the  matter  of  calculating-  dividends. 
The  matter  can  be  simplified  by  the  consultation  of 
a-  table,  which  can  be  made  out  once  for  all.  The 
following  formula  can  be  used  in  preparing  such 
a  table: 

(Fat — 3) X 1 4+5 •  i o— Amount  of  fat  and  casein  in 
100  pounds  of  milk. 

Such  a  table,  already  prepared,  is  here  given : 


Per  cent  of 
fat  in  milk 

Dividend 
number 

Per  cent  of 
fat  in  milk 

Dividend 
number 

3.00 

5.10 

4.05 

6.57 

3.05 

5.17 

4.10 

6.64 

3.10 

5.24 

4.15 

6.71 

3.15 

5.31 

4.20 

6.78 

320 

5.38 

4.25 

6.85 

3.25 

5.45 

4.30 

6.92 

3.30 

5.52 

4.35 

6.99 

3-35 

5.59 

4.40 

7.06 

3.40 

5.66 

4.45 

7.13 

3.45 

5.73 

4.50 

7.20 

3.50 

5.80 

4.55 

7.27 

3.55 

5.87 

4.60 

7.34 

360 

5.94 

4.65 

7.41 

3.65 

6.01 

4.70 

7.48 

3.70 

6.08 

4.75 

7.55 

3.75 

6.15 

4.80 

7.62 

3.80 

6.22 

4.85 

7.69 

3.85 

6.29 

4.90 

7.77 

3.90 

6.36 

4.95 

7.84 

3.95 

6.43 

5.00 

7.90 

4.00 

6.50 

(5)  The  introduction  of  the  fat-test  is  called  for 
by  this  method,  and  thus  a  great  step  in  advance 
would  be  made  in  comparison  with  the  weight-of- 
milk  method.  This  might  ultimately  lead  to  the  adop- 
tion of  the  simple  fat  basis. 

The  following  objections  to  such  a  method  may  be 
suggested : 


PAYING    FOR    MILK    FOR    CHEESE-MAKING          2/9 

(1)  It   aims   to   pay   for   the   amount   of   cheese 
produced   without   regard  to  composition   or  quality. 
Of  course,  this  same  objection  applies  to  the  fat-and- 
casein  method  and  the  fat-plus-two  method. 

(2)  The      method      of     calculation      may     give 
amounts    of    casein    differing     from    those    actually 
present  in  milk.       In  individual  cases  and  for  single 
tests,   this    might   be   true,    but,    taking   the    average 
of    a     whole     season,     the     differences    would     not 
usually    be    found    great,    and    the    season's    average 
would  be  the  factor  on  which  to  base  a  comparison 
as  to  accuracy.       As  a  matter  of  fact,  in  the  case 
of  the  50  herds  already  referred  to,  in  no  case  was 
there    a    difference  in    the    season's    results    greater 
than  0.25  per  cent  of  casein  between  the  calculated 
amount  and  that  obtained  by  the  chemical  method; 
while  in  the  case  of  40  out  of  50  patrons  the  results 
differed  by  less  than  o.i   per  cent,  in  several  cases 
being    identical.       The    casein-test,    even    in    skillful 
hands,  may  give  results  that  differ  as  much  as  0.2  per 
cent  from  the  regular  chemical  method. 

METHODS  OF  CALCULATING  DIVIDENDS 
AT  CHEESE-FACTORIES 

In  concluding  this  chapter,  we  will  illustrate 
somewhat  more  in  detail  how  dividends  at  cheese- 
factories  are  calculated  according  to  the  different 
methods  that  have  been  discussed.  For  this  pur- 
pose, we  will  make  use  of  the  following  data  which, 
for  convenience,  are  given  here  in  a  body  for  refer- 
ence. In  all  cases,  the  following  three  items  must 
be  known :  ( I )  The  amount  of  milk  delivered  by 


28O     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


each  patron  during  the  dividend  period;  (2)  total 
or  gross  amount  of  money  received  for  the  cheese 
produced  during  the  same  period;  and  (3)  the  ex- 
penses to  be  deducted  from  gross  receipts,  such  as 
cost  of  manufacture,  cheese-boxes,  cartage,  selling, 
etc. 


Name 
of 
patron 

Pounds  of  milk 
delivered  dur- 
ing dividend 
period 

Pounds  of 
cheese  for 
100  pounds  of 
milk 

Per  cent 
of  fat 
in  milk 

Per  cent 
of  casein 
in  milk 

Pounds  of 
cheese  made 
from  milk 
delivered  by 
each  patron 

A 

350 

10.6 

4.0 

2.50 

37.1 

B 

650 

9.7 

3.6 

2.34 

63.0 

C 

835 

13.3 

5.2 

2.98 

111.0 

D 

965 

11.5 

4.4 

2.68 

111.0 

E 

1200 

11.1 

4.2 

2.58 

133.2 

Totals 

4000 

455.3 

From  the  stated  amounts  of  milk  there  are  made 
455.3  pounds  of  cheese.  We  will  suppose  that  this 
is  sold  at  a  price  which  realizes  10  cents  a  pound, 
or  $45.53,  after  all  expenses  are  deducted. 

Calculating  dividends  on  basis  of  weight  of  milk. 
— In  the  table  preceding  we  have  a  total  of  4,000 
pounds  of  milk  furnished  in  the  dividend  period 
and  the  cheese  made  from  this  nets  $45.53.  Divid- 
ing this  sum  of  money  by  the  number  representing 
the  pounds  of  milk  delivered  (4,000),  we  find  the 
net  receipts  from  i.o  pound  of  milk  to  be  1.138 
cents.  This  amount  is  multiplied  by  the  number 
representing  the  pounds  of  milk  furnished  by  each 
patron  and  the  result  gives  the  amount  of  the  divi- 
dend of  each.  The  results  are  given  in  the  following 
table : 


PAYING   FOR    MILK   FOR   CHEESE-MAKING          28l 


Name 
of 
patron 

Pounds 
of  milk 
delivered 

Value 
of  1.0 
pound 
of  milk 

Divi- 
dend of 
each  for 
period 

Pounds 
of  cheese 
made  from 
milk  fur- 
nished by 
each 

Money 
received 
for  each 
pound  of 
cheese 

Money  re- 
ceived for 
each  pound 
of  milk-fat 
furnished 

Cents 

Cents 

Cents 

A 

350 

1.138 

$3.98 

37.1 

10.73 

28.4 

B 

650 

7.40 

63.0 

11.75 

31.1 

C 

835 

" 

9.51 

111.0 

8.57 

21.9 

D 

965 

" 

10.98 

111.0 

9.90 

25.9 

E 

1200 

13.66 

L33.2 

10.26 

27.1 

The  figures  in  the  last  two  columns  emphasize  the 
fact  that  this  method  of  paying  for  milk  gives  results 
that  have  little  or  no  relation  to  the  cheese-produc- 
ing values  of  the  milk.  It  is  fair  to  all  only  when 
the  milk  furnished  by  each  patron  is  of  the  same 
composition  and  cheese-producing  value  as  the  milk 
of  every  other  patron,  a  condition  rarely,  if  ever,  found 
to  exist. 

Calculating  dividends  on  basis  of  fat  in  milk. — 
Having  the  data  already  given  above  in  the  table  on 
p.  280  we  multiply  the  amount  of  milk-fat  delivered 
by  each  patron  by  the  net  price  realized  for  one  pound 
of  fat.  We  will  consider  the  method  in  three  separate 
steps. 

Step  i.  To  find  the  number  of  pounds  of  milk- fat 
furnished  by  each  patron,  multiply  in  each  case  the 
weight  of  milk  by  the  number  indicating  the  per  cent 
of  fat  and  divide  the  result  by  100. 

Step  2.  Find  the  net  value  of  one  pound  of  milk- 
fat  by  dividing  the  total  net  receipts  by  the  total  num- 
ber of  pounds  of  fat  delivered  by  all  the  patrons 
during  the  dividend  period. 


282     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


Step  3.  Multiply  the  number  of  pounds  of  fat  de- 
livered by  each  patron  by  the  net  price  received  for  one 
pound  of  fat. 

Example:  Step  i.  The  data  and  results  are  indi- 
cated in  tabular  form,  as  follows: 


Name  of 
patron 

Pounds  of  milk 
delivered  during 
dividend  period 

Per  cent 
of  fat 
in  milk 

Pounds  of  fat 
in  milk 
delivered 

A  
B 

350 
650 

x      4.0 
x      3.6 

=      14.00 
=      23.40 

C  

835 
965 

x      5.2 
X      4.4 

=      43.42 
=      42.46 

1200 

x      4.2 

=      50.40 

Total  number  of  pounds  of  fat  delivered  by  all  patrons 


173.68 


Step  2.  From  the  amount  of  milk  indicated  above, 
the  amount  of  cheese  made  was  455.3  pounds,  which 
realized  10  cents  a  pound  after  deducting  all  ex- 
penses, making  a  total  of  $45.53.  This  sum  divided 
by  173.68,  the  total  pounds  of  fat  delivered,  gives 
26.2  cents  as  the  net  price  received  for  each  pound 
of  fat. 

Step  3.  The  data  and  results  are  indicated  in 
tabular  form,  as  follows: 


Name  of 
patron 

Pounds 
of  fat 
delivered 

Net  price  re- 
ceived for  fat 
per  pound 

Amount  of 
dividend  due 
each  patron 

Net  price  re- 
ceived for 
cheese  per  Ib. 

A... 
B 

14.00 
23  40 

Cents 
x      26.2 
x      26  2 

=   $  3.67 
=        6.14 

Cents 
9.90 
9.75 

C... 

43  42 

x      26.2 

=      11.38 

10.25 

D  
E 

42.46 
50  40 

X      26.2 
X      26  2 

=      11.13 
=      13.21 

10.03 
9.92 

PAYING    FOR    MILK    FOR    CHEESE-MAKING 


Calculating  dividends  on  basis  of  yield  and  rela- 
tive value  of  cheese-solids. — By  this  method  one 
proceeds  exactly  as  in  case  of  the  fat-basis  method, 
except  that  in  place  of  the  percentages  of  fat,  one 
uses  the  number  obtained  from  the  table  (p.  262)  cor- 
responding in  each  case  to  percentage  of  fat  in  milk 
and  the  lactometer  reading. 

Calculating  dividends  on  basis  of  milk-fat  plus 
two. — The  following  table  indicates  the  general  method 
of  procedure : 


Pounds 

Pounds 

of   fat 

of  milk 

and 

Price 

Amount 

Net 

Net 

Name 
of 
patron 

de- 
livered 
during 
divi- 

Per cent  of 
fat  in  milk 
+  2  (casein) 

casein 
fur- 
nished 
corre- 

of each 
pound 
of  fat 
and 

of  divi- 
dend 
due 
each 

price  re- 
ceived 
for 
cheese 

price  re 
ceived 
for  fat 
per 

dend 
period 

spond- 
ing to 

casein 

patron 

per 
pound 

pound 

fat+  2 

Cents 

Cents 

A..  . 

350 

x  (4.0x2=)6.0 

-  21.0 

x   17.95 

=   $3.77 

10.16 

27.0 

B 

650 

x  (3  6x2=)5  6 

=    36.4 

x    17  95 

=      6  54 

10  40 

28.0 

C  

835 

x  (5.2x2=)7.2 

=    60.1 

x    17.95 

=    10.78 

9.71 

24.8 

D  

965 

x  (4.4x2=)6.4 

-   61.8 

x    17.95 

=    11.10 

10.00 

26.1 

E  

1200 

X  (4.2X2=)6.2 

-    74.4 

x    17.95 

-    13.34 

10.02 

26.5 

In  explanation  of  the  foregoing  table,  it  is  seen 
that  the  amount  of  milk  furnished  by  each  patron  is 
multiplied  by  the  per  cent  of  fat  plus  two.  These 
results  are  added  and  the  sum  (amounting  to 
253.7)  divided  into  the  amount  of  money  received 
for  the  cheese  ($45.53),  giving  17.95  cents  as  the 
value  of  each  pound  of  mixed  fat  and  casein  (rep- 
resented by  2  pounds  of  casein  in  100  pounds  of 
milk).  The  number,  obtained  in  each  case  by  mul- 
tiplying the  number  of  pounds  of  milk  furnished  by 


284     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


the  number  representing  the  per  cent  of  milk-fat4-2, 
is  then  multiplied  by  17.95,  the  result  being  the 
dividend  in  each  case.  It  is  noticed  that  this  method 
makes  a  pound  of  cheese  or  of  milk-fat  yield  larger 
money  returns  in  case  of  poor  than  in  case  of  rich 
milk. 

Calculating  dividends  on  basis  of  fat  and  casein. 
— The  same  process  is  followed  as  before,  except 
that  the  yield  of  fat  and  casein,  taken  together,  con- 
stitutes the  basis  of  division.  The  percentages  of 
fat  and  of  casein  in  milk  are  added  together,  in  each 
case,  and  the  sum  multiplied  by  the  number  of 
pounds  of  milk  furnished,  thus  giving  the  number 
of  pounds  of  fat  and  casein  furnished  by  each  patron. 
The  total  amount  of  fat  and  casein  furnished  by  all 
the  patrons  for  the  dividend  period  (279.36  pounds) 
is  divided  into  the  net  proceeds  from  the  sale  of  cheese 
and  the  result  is  the  net  dividend  value  (16.3  cents) 
of  one  pound  of  mixed  fat  and  casein.  This  figure 
is  then  multiplied  by  the  amount  of  fat  and  casein 
furnished  by  each  patron.  The  details  are  indicated 
below. 


Name 
of 

Pounds 
of  milk 
delivered 

Per  cent  of 
fat  and 

Pounds  of 
fat  and 

Amount 
of  divi- 
dend 

Net 
price 
received 
for 

Net 
price 
received 

patron 

during 
dividend 
period 

casein 
in  milk 

casein 
furnished 

each 
patron 

cheese 
per 
pound 

for  fat 
per 
pound 

Cents 

Cents 

A  

350 

x(4.0x2.50=)6.50 

=  22.75x16.3=   $3.71 

10.00 

26.5 

B  

650 

x(3.  6X2.  34=)5.94  =38.61x16.3  =      6.29 

10.00 

26.8 

C.... 

835 

x(5.  2x  2.  98=)8.  181  =  68.30X16.  3  =    11.13 

10.00 

25.6 

D.... 

965 

X(4.4X2.68=)7.08I  =  68.32X16.3 

=    11.14 

10.00 

26.2 

E  

1200 

x(4.2x2.58=)6.78 

=  81.38X16.3 

=    13.26 

10.00 

26.3 

CHAPTER  XXII 

The  Relations  of  Micro-Organisms  and 
Enzyms  to  Cheese-Making 

Milk,  on  standing  under  ordinary  conditions,  under- 
goes a  variety  of  changes  sooner  or  later,  many  of 
which  destroy  its  value  for  cheese-making  purposes. 
The  most  common  and  extensive  changes  occurring 
in  milk  are  due  to  fermentations.  One  result  of  some 
kinds  of  fermentation  is  the  production  of  bad  flavors, 
but  these  may  be  acquired  also  by  direct  absorption 
from  the  surrounding  air  or  from  the  food  consumed 
(p.  6).  We  shall  see  that  certain  kinds  of  fermenta- 
tions are  useful  and  necessary  in  cheese-making,  while 
others  make  it  difficult  or  impossible  to  prepare  a  good 
product. 

FERMENTATIONS  AND  FERMENTS 

The  souring  of  milk  is  one  of  the  most  familiar 
cases  of  fermentation.  The  important  change  taking 
place  is  the  formation  of  lactic  acid  from  milk-sugar 
and  the  change  is  caused  by  certain  living  organisms^ 
An  equally  familiar  case  of  fermentation  is  the 
coagulation  of  milk  by  rennet-extract.  In  this  case 
the  change  is  produced,  not  by  a  living  organism,  but 
by  a  chemical  substance.  That  which  causes  fermenta- 
tion is  called  a  ferment. 

Fermentation  may  be  defined  as  a  chemical  change 
of  an  organic  compound  through  the  action  of  living 

285 


286     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

organisms  or  of  chemical. agents.  We  thus  have  two 
general  kinds  of  ferments,  (i)  organized  ferments 
and  (2)  unorganized  ferments,  known  also  as  chem- 
ical ferments  or  enzyms.  In  the  illustrations  given 
above,  the  ferments  are  ( I )  lactic  acid  organisms  and 
(2)  rennet  ferment;  in  one  case  the  organic  matter 
cjianged  is  milk-sugar;  in  the  other,  milk-casein. 
Organized  ferments  are  living  micro-organisms, 
capable,  as  a  result  of  their  growth,  of  causing  fer- 
mentations. Unorganized  ferments  are  chemical  sub- 
stances, or  ferments  without  life,  capable  of  causing 
marked  changes  in  many  complex  organic  compounds, 
the  enzyms  themselves  undergoing  little  or  no  change. 

General  characteristics  of  ferments. — Ferments 
possess  certain  general  characteristics  in  common, 
among  which  may  be  mentioned  the  following:  (i) 
A  very  small  amount  of  ferment  is  capable  of  pro- 
ducing very  great  changes.  (2)  They  are  all  de- 
pendent upon  temperature  as  a  condition  of  activity. 
They  cease  to  act  at  low  and  also  at  high  tempera- 
tures. Most  of  them  find  the  temperature  that  is 
best  suited  to»  their  greatest  activity  between  80°  and 
100°  F.  (3)  Ferments  are  destroyed  by  heat,  the 
temperature  of  boiling  water,  in  most  cases,  com- 
pletely destroying  their  power  to  act.  Their  activity 
•is  checked  by  low  temperatures,  but,  when  again 
warmed,  they  renew  their  activity.  (4)  The  action 
of  ferments  is  checked  or  prevented  by  many  sub- 
stances. (5)  When  the  products  formed  by  ferments 
accumulate  in  certain  amounts,  the  ferment  action 
usually  stops.  (6)  All  ferments  are  closely  con- 
nected with  living  processes. 

Organized  ferments,  or  living  micro-organisms 
capable  of  causing  fermentations,  are  divided  into 


MICRO-ORGANISMS   AND    ENZYM8  287 

several  classes;  but  those  of  greatest  interest  in  con- 
nection with  cheddar  cheese-making  are  called  bac- 
teria. These  are  the  smallest  conceivable  forms  of 
plant  life.  Each  individual  consists  of  a  single  cell, 
averaging  in  diameter  one-thirty-thousandth  of  an 
inch. 

(i)  Kinds. — Bacteria  appear  in  three  general 
varieties  of  form:  (a)  Ball  (coccus),  (b)  short  rod 
(bacillus),  and  (c)  corkscrew  (spirillum).  (Figs. 
39-42.) 


FIG.    39 — BALL-SHAPED    BAG-  FIG.    40 — CHAINS    OF    BALL- 

TERIA     (COCCUS).  SHAPED     (COCCUS)     BAC- 

( Rogers)  TERIA 

(Rogers) 

(2)  Method  of  growth  and  reproduction. — They 
multiply  in  number,  or  reproduce,  by  simple  division; 
that  is,  when  a  cell  grows  in  size,  it  increases  more 
in  one  direction,  so  as  to  result  in  lengthening  out 
slightly,  and  a  partition  forms  across  the  cell,  thus 
producing  two  new  cells  in  place  of  the  old  one ;  and 
then  each  of  these  subdivides  again  and  so  on  con- 
tinuously. Some  kinds  of  bacteria  form  spores  in 
the  cells;  these  are  to  bacteria  what  seeds  are  to 


SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


higher  plants.  Spores  are  not  so  easily  killed  by  heat 
as  are  bacteria.  Under  favorable  conditions,  the 
rapidity  of  growth  of  bacteria  is  remarkable.  Thus, 
in  some  cases,  one  cell  divides  into  two  cells  in  2Q 
minutes;  if  this  rate  were  kept  up  for  24  hours,  the 
one  cell  would  multiply  into  several  millions. 

(3)  Food  requirements  of  bacteria. — Bacteria  re- 
quire as  food  for  satisfactory  growth  compounds  con- 
taining nitrogen,  carbon,  hydrogen  and,  in  addition, 


FIG.     41 — ROD-SHAPED     BAC- 
TERIA   (bacillus).    CLEAR 

AREAS  IN  SOME  ARE 

SPORES.          (Rogers) 


FIG.  42 — B  A  C  T  E  R  I  A  WITH 
HAIR-LIKE  ORGANS,  WHICH 
THEY  USE  IN  MOVING 
THEMSELVES  ABOUT  IN 

LIQUIDS  (Rogers) 


small  amounts  of  inorganic  or  mineral  matter.  The 
sugar,  casein,  albumin  and  salts  in  milk  and  its 
products  furnish  a  supply  of  food  very  readily 
utilized  by  bacteria. 

(4)  Temperature. — The  bacteria  commonly  pres- 
ent in  milk  grow  between  the  limits  of  40°  and  110° 
F.,  the  most  favorable  limits  being  between  80°  and 
95°  F.  Many  bacteria  are  killed  between  130°  and 


MICRO-ORGANISMS    AND    ENZYMS  289 

140°  F.,  when  exposed  to  this  heat  for  ten  minutes, 
and  most  of  them  are  destroyed  at  185°  F.  Many 
spores  are  killed  at  temperatures  only  above  212° 
F.,  and  even  then  require  heating  one  to  three"  hours. 
(Fig.  43.)  Dry  heat  is  less  effective  than  moist  heat. 
Live  steam,  therefore,  affords  a  most  effective  means 
of  destroying  bacteria.  All  bacteria  are  rendered  in- 
active at  low  temperatures  and  some  may  be  killed 
by  intense  cold.  Many  bacteria  may  retain  life  on 
being  dried  and  become  active  again  when  placed 
under  favorable  conditions  of  moisture  and  tem- 
perature. 

(5)  Action  of  sunlight,  chemicals,  etc. — Sunlight 
kills   many  bacteria  when  they  are   exposed   directly 
to  the  sun's  rays  for  a  few  hours.     Bacteria  are  either 
checked  in  growth  or  killed  by  many  different  chem- 
ical    compounds.       Those     compounds     that     simply 
retard  the  rapidity  of  growth  of  bacteria  are  called 
antiseptics,  among  which  are  carbolic  acid,  salt,  salt- 
peter, etc. ;  those  that  destroy  bacterial  life  are  called 
disinfectants,  among  which  are  mercuric  chlorid  (cor- 
rosive   sublimate),    formaidehyd     (formalin),    potas- 
sium  bichromate,    chloroform,    etc.     The   activity    of 
each  kind  of  bacteria  is  stopped  by  an  accumulation 
of  products  formed  by  it  and,  in  some  cases,  by  the 
products   of  activity   of  other  bacteria.     Thus,   most 
kinds  of  lactic  acid  bacteria  stop  growing  when  about 
0.9  per  cent  acid  is  formed,  and  much  less  than  this 
amount   of  lactic   acid  also   prevents   the   growth   of 
many  other  bacteria. 

(6)  Changes   produced. — In   the   course   of   their 
growth,     bacteria     produce     great     changes     in     the 
materials   in   which   they  grow ;    and  the  process  by 
which  these  changes  are  brought  about  are  known, 


2QO      SCIENCE  AND  PRACTICE  OF  CHEESE-MAKING 


WATER  BOILS  212—  =  I— J 


BACTCRIA 


BUOOO  HEAT.—E 


--GROWTH  CEASES. 


MOST  RAPID. 


-GROWTH  RETARDED. 


WATER  FREEZES  O2.-H  L.  GROWTH  CEASES, 


FIG.  43 — INFLUENCE  OF  TEMPERATURE  ON  BACTERIA  ORDINARILY 

FOUND  IN  MILK     (Rogersj. 


MICRO-ORGANISMS   AND   ENZYMS  29! 

as  previously  stated,  under  the  general  name  of  fer- 
mentation. 

(7)  Distribution. — Bacteria  are  found  distributed 
nearly  everywhere  in  the  soil,  in  the  air  and  in  water. 
They  are  always  present  in  large  numbers  wherever 
vegetable  or  animal  matter  is  undergoing  decay.  They 
are,  therefore,  always  closely  associated  with  dirt  and 
filth.  While  some  are  the  causes  of  dreaded  diseases 
and  of  serious  troubles  in  cheese-making,  most  of 
them  are  either  harmless  or  actively  helpful  in  many 
ways. 

Unorganized  ferments  or  enzyms. — Many  enzyms 
are  produced  directly  by  bacteria  and  are  the  direct 
agents  producing  the  observed  changes  of  bacterial 
activity,  while  many  are  formed  in  higher  plants  and 
in  animals.  Thus,  the  pepsin  found  in  the  human 
stomach  is  an  enzym;  its  special  power  or  form  of 
activity  enables  it  to  change  protein  compounds  from 
insoluble  to  soluble  forms.  The  ptyalin  contained  in 
saliva  is  another  enzym  and  is  capable  of  changing 
starch  into  sugar.  Enzyms  are  destroyed  by  high 
temperatures  and  by  many  disinfectants.  Some  sub- 
stances, like  ether,  chloroform  and  formaldehyd,  do 
not  seriously  interfere  with  the  activity  of  enzyms, 
while  they  do  destroy  bacteria. 

In  connection  with  the  subject  of  ferments,  we 
shall  consider  the  following  ones  as  those  of  most 
importance  in  connection  with  cheese-making:  (i) 
Lactic  acid  bacteria,  (2)  gas-producing  bacteria,  (3) 
digesting  bacteria,  (4)  bacteria  producing  undesir- 
able flavors,  (5)  yeasts,  (6)  milk-enzyms,  (7)  rennet- 
enzyms,  and  (8)  pepsin.  The  ferments  that  are 


292     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


responsible  for  many  of  the  defects  found  in  Amer- 
ican cheddar  cheese  will  be  discussed  only  briefly  here, 
because  their  relations  to  cheese-making  are  fully 
treated  from  a  practical  standpoint  in  Part  II,  pp. 
HS-I30. 

LACTIC  ACID  FERMENTATION 

The  ordinary  souring  of  milk  is  due  to  the  forma- 
tion of  lactic  acid,  which  is  produced  by  the  action 
of  lactic  acid  bacteria  (Bacillus  lactici  acidi.  Fig.  44) 
upon  the  sugar  in  milk.  A  large  number  of  different 

kinds  or  types  of  bacteria 
are  able  to  produce  lactic 
acid  from  milk-sugar. 
Some  interesting  work 
has  been  done  recently 
(Bull.  No.  42,  Mich. 
Agr.  Coll.  Exp.  Sta.) 
which  shows  that  other 
micro-organisms  are  often 
associated  with  the  micro- 
organisms of  lactic  fermen- 
tation and  that  these 
associate  micro-organisms 
often  have  the  power  of  furnishing  products  that 
exert  a  decided  influence  upon  the  rapidity  of  the 
growth  of  the  lactic  micro-organisms. 

We  have  already  (p.  150)  called  attention  to 
the  fact  that  the  sour  taste  of  milk  is  not  due  to  the 
presence  of  uncombined  lactic  acid,  since  little  or  no 
free  lactic  acid  is  present  in  sour  milk  until  it  has 
quite  a  high  degree  of  acidity :  but  is  due  to  acid  phos- 
phate of  calcium,  which  is  formed  by  the  action  of 
lactic  acid  upon  the  insoluble  calcium  compounds  in 


FIG.       44 — TYPICAL      LACTIC- 
ACID  BACTERIA     (Rogers) 


MICRO-ORGANISMS   AND   ENZYMS  293 

the  milk.  Milk  begins  to  taste  sour  when  its  acidity 
amounts  to  about  0.3  per  cent;  which  really  means 
when  a  little  over  0.2  per  cent  of  lactic  acid  has  been 
formed  from  milk-sugar;  because  the  milk-casein 
itself  and  the  soluble  phosphates  have  an  acidity  of 
nearly  o.io  per  cent  (p.  153)  when  the  milk  is 
freshly  drawn  and  no  milk-sugar  has  had  a  chance 
to  be  changed  into  lactic  acid.  According  to  recent 
work  done  at  the  New  York  experiment  station, 
milk  curdles  on  boiling  when  the  acidity  reaches 
0.32  to  0.46  per  cent,  and  at  ordinary  room  tempera- 
ture when  it  reaches  0.58  to  0.72  per  cent.  When 
artificial  lactic  acid  is  added  directly  to  fresh  milk, 
curdling  takes  place  on  boiling  when  the  acidity 
reaches  0.36  per  cent  and  at  room  temperature  when 
the  acidity  reaches  0.57  per  cent.  Bacteria  continue 
actively  converting  milk-sugar  into  lactic  acid, 
until  the  amount  of  acid  reaches  0.8  to  i.o  per  cent 
of  the  milk ;  and  then  they  greatly  dimmish  or  cease 
their  activity,  because  they  cannot  thrive  in  a  solu- 
tion showing  this  amount  of  acidity.  Their  activity 
is  thus  stopped  by  the  accumulation  of  the  chief 
product  of  their  own  activity,  and  not  because  the 
supply  of  milk-sugar  runs  out;  for,  when  their 
activity  ceases,  about  three-quarters  of  the  milk- 
sugar  remains  still  unconsumed.  Products  besides 
lactic  acid  are  formed,  varying  according  to  tem- 
perature and  other  conditions.  In  recent  work  at 
the  New  York  experiment  station,  we  have  ob- 
tained, in  the  form  of  lactic  acid,  about  80  per  cent 
of  the  milk-sugar  that  was  decomposed.  In  connec- 
tion with  cheese-making,  the  total  acidity  of  the  whey 
may  rise  as  high  as  1.2  per  cent.  Under  conditions, 
which  are  not  present  in  cheddar  cheese-making, 
some  micro-organisms  may  produce  as  much  as  3 


294     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

per  cent  of  lactic  acid,  decomposing  a  correspond- 
ing amount  of  milk-sugar. 

The  range  of  temperature  most  favorable  to  lactic 
acid  organisms  is  90°  to  95°  F.  Below  80°  F.  their 
activity  gradually  decreases  and  practically  ceases  at 
50°  F.  At  105°  F.,  they  are  fairly  inactive;  many 
are  killed  at  135°  to  140°  F.,  and  all  at  150°  to 
160°  F. 

While  the  lactic  acid  fermentation  spoils  milk  for 
the  taste  of  most  people,  at  least  for  ordinary  uses,  it 
is  a  very  essential  factor  in  the  manufacture  of  cheese. 
Very  few  lactic  acid  bacteria  are  found  in  fresh  milk, 
but  they  increase  so  rapidly  at  ordinary  temperature 
(70°  F.)  that  in  12  to  18  hours  they  generally  exceed 
in  number  all  other  bacteria  in  milk.  In  summer 
weather,  when  the  temperature  is  especially  favorable 
to  their  rapid  growth,  the  lactic  acid  bacteria  usually 
constitute,  at  the  time  the  milk  sours,  more  than  95 
per  cent  of  all  the  micro-organisms  in  the  milk. 

While  the  growth  of  lactic  acid  organisms  in  milk 
is  favored  by  the  presence  of  a  small  amount  of  acid, 
most  other  organisms  do  not  thrive  so  well  in  an  acid 
environment.  Therefore,  as  soon  as  enough  milk- 
sugar  has  been  converted  into  lactic  acid  to  produce 
a  slightly  acid  condition,  other  organisms  decrease 
in  activity,  while  the  lactic  acid  organisms  vigorously 
increase,  unhindered.  It  is  quite  commonly  thought 
that  milk  is  peculiarly  liable  to  sour  during  thunder- 
storms, as  the  result  of  some  peculiar  electrical  con- 
dition or  other  mysterious  influence.  The  hot  weather 
preceding  such  storms  favors  the  more  rapid  growth 
of  the  lactic  acid  bacteria  and  this  is  a 'sufficient  ex- 
planation, and  the  proper  one.  Milk  free  from  such 
micro-organisms  never  sours  during  thunderstorms. 


MICRO-ORGANISMS    AND    ENZYMS 

The  lactic  acid  fermentation  we  have  been  con- 
sidering is  what  we  may  call  the  normal  form,  the 
particular  form  we  desire  to  have  present  in  milk  in 
cheese-making.  Their  presence  is  insured  by  the  use 
of  good  starters  (p.  18).  Milk  in  which  this  form 
of  lactic  fermentation  has  occurred  produces,  in 
souring,  a  firm  curd  free  from  gas  bubbles  and  with 
only  a  little  whey  on  the  surface.  When  agitated, 
the  curd  breaks  apart  readily  into  small  particles, 
which  settle  slowly  and  leave  a  clear  whey.  The 
milk  should  have  a  pleasant,  clean,  acid  taste,  en- 
tirely free  from  anything  resembling  a  tainted  flavor. 
So  far  as  we  know,  the  lactic  acid  bacteria  belonging 
to  this  normal  group  never  form  products  of  a  poison- 
ous character. 

GAS-PRODUCING  BACTERIA 

Some  of  the  bacteria  that  decompose  milk-sugar 
with  formation  of  lactic  acid  are  usually  grouped  with 
the  lactic  acid  bacteria,  though  they  possess  distinguish- 
ing characteristics  which  mark  them  as  abnormal,  so 
far  as  their  behavior  in  cheese-making  is  concerned. 
While  they  decompose  milk-sugar  and  produce  lactic 
acid,  they  produce  other  products  besides,  especially 
gases;  they  may  also  produce  volatile  products  that 
are  offensive.  These  bacteria  are  responsible  for  many 
of  the  defects  in  cheese  (pp.  116-130).  When  gas- 
producing  ferments  are  present  in  milk,  they  are 
usually  responsible  for  increased  losses  of  fat  in  the 
cheese-making  process. 

DIGESTING  BACTERIA 

A  large  group  of  bacteria  curdle  milk  without  sour- 
ing it  and  then  slowly  digest  or  dissolve  the  curd; 


296     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

therefore,  they  are  often  called  "liquefiers."  These 
effects  are  due  to  enzyms  which  are  produced  by  the 
bacteria.  Some  of  these  bacteria  form  products  that 
are  offensive  in  flavor ;  some  produce  gases,  and  some, 
acid.  They  may  be  a  source  of  serious  trouble  in 
cheese-making  in  the  production  of  gassy  curd  and 
offensive  flavors  in  cheese.  They  may  also  cause 
some  dissolving  of  the  curd,  in  which  case  the  loss  of 
fat  is  unusually  large.  These  bacteria  are  widely  dis- 
tributed, being  found  in  stable  filth,  in  soil,  water  and 
floating  dust.  They  are  nearly  always  present  to  some 
extent  in  milk.  Fortunately,  their  activity  is  checked 
by  the  presence  of  lactic  acid,  and  the  easiest  method 
of  controlling  such  ferments  in  cheese-making  is  to 
make  conditions  favorable  for  the  rapid  growth  of 
normal  lactic  acid  bacteria;  thi-6  is  usually  accom- 
plished by  the  use  of  a  pure  starter.  The  growth  of 
digesting  bacteria  in  milk  is  favored  by  high  tempera- 
ture; consequently,  in  hot  weather,  when  the  high 
temperature  favors  the  growth  of  the  digesting  bac- 
teria more  than  it  does  the  lactic  acid  organisms,  the 
undesirable  forms  get  beyond  control  and  seriously 
impair  the  operations  and  results  of  cheese-making. 

BACTERIA    PRODUCING    UNDESIRABLE 
FLAVORS 

Different  bacteria  are  responsible  for  many  different 
kinds  of  bad  flavors  in  milk  and  cheese,  among  which 
are  the  following:  Bitter  (p.  119),  fishy,  rancid  or 
butyric  acid,  hydrogen  sulphid  (p.  116). 

YEASTS 

Yeasts  are  micro-organisms  resembling  bacteria  in 
some  respects,  but  usually  larger.  They  are  very 


_ 


MICRO-ORGANISMS   AND   ENZYMS  297 

widely  distributed  and  are  common  in  milk.  The  con- 
ditions usually  present  in  milk  are  not  favorable  to 
their  growth  and  they  are  not,  therefore,  the  source 
of  trouble  so  often  as  are  bacteria.  Among  the  effects 
which  can  be  attributed  to  the  action  of  different 
yeasts  are  the  formation  of  bitter  and  of  fruity  flavors 
(pp.  118,  126). 

MILK-ENZYMS 

Milk  contains  several  different  enzyms.  Some  of 
them,  at  least,  are  of  bacterial  origin.  It  would  take 
us  too  far  from  the  purpose  of  this  discussion  to  go 
into  details  relating  to  milk-enzyms.  We  shall  con- 
fine our  attention  to  the  one  known  as  galactase.  In 
1897,  Babcock  and  Russell  announced  the  discovery 
of  an  unorganized  ferment  or  enzym  in  milk  to  which 
they  gave  the  name  of  galactase.  They  were  led  to 
this  discovery  by  observing  that  fresh  milk  coagu- 
lates, even  when  obtained  as  free  as  possible  from 
bacteria,  and  when  all  bacterial  activity  has  been 
stopped  by  treatment  with  ether  or  chloroform.  The 
milk  first  coagulates  and  then  the  curd  gradually  dis- 
solves. Having  excluded  the  seeming  possibility  of 
bacterial  action  in  the  milk  after  it  was  drawn,  they 
concluded  that  the  observed  coagulating  and  dissolv- 
ing action  must  be  due  to  enzym  action,  probably  two 
different  enzyms.  Galactase  is  probably  a  mixture 
of  two  or  more  different  enzyms,  since  it  has 
been  shown  that  separator-slime,  when  treated  accord- 
ing to  Babcock  and  Russell's  method  in  preparing 
galactase  contains  at  least  three  distinct  enzyms, 
galactase  proper,  peroxidase  and  catalase.  The  dis- 
tinctive feature  of  the  action  of  galactase  is  its  power 


298     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


to    change    insoluble    proteins    like    milk-casein    into 
soluble  forms. 

The  following  have  been  given  as  some  of  the  more 
prominent  characteristics  of  galactase.  ( i )  Galac- 
tase  readily  attaches  itself  to  finely  divided  particles 
in  suspension  like  milk-casein  and  fat-globules ;  hence, 
it  is  found  in  separator-slime  and  in  cream  to  a  greater 
extent  than  in  milk  or  skim-milk.  (2)  The  most 
favorable  temperature  for  the  action  of  galactase  lies 
between  98°  and  108°  F.  Heated  for  ten  minutes 
above  168°  F.,  its  activity  is  destroyed,  as  shown  by 
the  following  table : 

EFFECT  OF   HEAT   ON   GALACTASE   IN    MILK 


Temperature  used 
in  heating  milks 

Age  of  milks 
when 
analyzed 

Soluble  nitrogen  expressed 
in  percentage  of  nitrogen 
in  milk    • 

Degrees 
90°C.(194°F. 
8S°C.(18S°F. 
85°C.(185°F. 
9S°C.(203°F. 
95°C.(203°F: 
98°C.(208°F. 

Months 
13 
8 
7 
15 
16 
14 

Per  cent 
4.26 
10.8 
9.7 
5.52 
5.5 
11.5 

(3)  Free  acids,  especially  hydrochloric  acid,  retard 
the  activity  of  galactase.  Neutral  or  alkaline  reac- 
tions favor  its  action.  (4)  Many  disinfectants,  like 
mercuric  chlorid,  carbolic  acid,  formaldehyd,  carbon 
disulphid,  etc.,  retard  or  prevent  the  action  of  galac- 
tase. (5)  Its  activity  is  greater  in  the  early  stage 
of  working,  as  measured  by  the  rapidity  with  which 
casein  is  changed  into  soluble  compounds. 

As  a  result  of  their  work,  Babcock  and  Russell 
concluded  that  galactase  is  a  trypsin-like  ferment, 


MICRO-ORGANISMS    AND    ENZYMS  2QQ 

except  that  one  of  its  most  distinctive  characteris- 
tics is  its  ability  to  form,  among  other  products, 
ammonia,  and  that,  therefore,  galactase  plays  a 
principal  role  in  cheese-ripening.  Their  galactase 
work  has  been  confirmed  to  the  extent  that  there  is 
in  milk  some  enzym  that  causes  more  or  less  de- 
composition of  milk-casein  and  of  cheese  paracasein 
in  the  presence  of  chloroform  or  ether.  In  work 
done  at  the  New  York  experiment  station,  the  ability 
of  galactase  to  form  ammonia  was  not  confirmed 
either  in  case  of  milk  or  cheese.  Cheese  kept  in  an 
atmosphere  of  chloroform  produced  no  ammonia  or, 
at  most,  only  slight  traces  even  at  the  end  of  15 
to  24  months.  Samples  of  the  cheese  were  sent  to 
the  Wisconsin  experiment  station,  and  the  absence  of 
ammonia  was  there  confirmed.  The  view  previously 
held  to  the  effect  that  galactase  was  able  to  account 
for  most  of  the  changes  in  cheese-ripening  was  then 
modified. 

RENNET-ENZYMS 

Rennet-extract  contains  one  or  two  unorganized 
ferments  or  enzyms.  There  has  long  been  a  differ- 
ence of  opinion  as  to  whether  there  is  in  rennet-extract 
one  enzym  which  acts  in  two  different  ways  or  two 
different  enzyms,  each  with  its  own  characteristic 
action.  So  far  as  the  essential  facts  are  concerned, 
rennet-extracts  possess  the  power  of  effecting  two 
distinct  kinds  of  changes:  (i)  coagulation  of  milk- 
casein  and  (2)  dissolving  or  digesting  the  milk-casein 
coagulum.  Those  who  regard  these  two  actions  as 
due  to  two  different  enzyms  contained  in  rennet  call 
the  coagulating  enzym  rennin  or  chymosin,  and  the 


3OO     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

dissolving  •  enzym,  pepsin.  The  best  evidence  at  hand 
at  present  rather  favors  the  existence  of  two  enzyms. 
For  our  purpose,  it  is  immaterial  whether  there  is  one 
enzym  or  more.  Our  chief  interest  in  rennet,  in  con- 
nection with  the  cheese-making  process,  lies  in  its 
characteristic  property  of  coagulating  milk-casein. 
Whether  the  dissolving  action  of  rennet-enzym  plays 
any  part  in  the  operation  of  cheese-making,  we  do 
not  know  at  present.  We  do  know,  however,  that  it 
has  some  action  in  the  cheese-ripening  process  (p. 

362). 

Source  of  rennet-enzym. — The  rennet-extract 
used  in  cheese-making  is  a  dilute  and  impure  form  ot 
rennet-enzym.  The  usual  source  of  rennet-extract  is 
the  fourth  stomach  of  a  suckling  calf.  It  is  also  pre- 
pared in  more  concentrated  condition  in  the  form  of 
powders  and  of  tablets.  Enzyms  having  the  same 
action  as  that  of  rennet  are  found  also  in  plants  and 
in  other  animals  than  calves.  Some  Bacteria  pro- 
duce a  coagulating  enzym  like  that  in  rennet. 

Home-made  rennet-extract. — Formerly,  cheese- 
makers  purchased  rennets  from  farmers  and  prepared 
the  extract  from  time  to  time  as  needed.  The  stomach 
of  a  freshly  slaughtered  calf  was  cleaned,  salted  and 
dried  by  farmers  and  sold  to  the  cheese-maker.  In 
preparing  the  home-made  extract,  a  number  of  ren- 
nets are  cut  in  pieces  and  just  covered  with  salt  brine 
in  a  suitable  vessel,  about  3  or  4  pounds  of  salt 
being  added  to  100  pounds  of  water.  The  mix- 
ture is  vigorously  stirred  and  pounded.  Once  a  week 
the  rennets  are  removed  from  the  brine  and  passed 
through  a  press  or  clothes-wringer  and  then  placed 
in  the  brine  again.  It  requires  about  four  weeks  to 


MICRO-ORGANISMS    AND    ENZYMS  30! 

complete  the  extraction.  The  solution  thus  obtained 
is  filtered  through  clean  straw,  sand,  and  charcoal  and 
then  treated  with  enough  salt  to  prevent  decomposi- 
tion; a  brine  containing  6  or  7  pounds  of  salt  to  100 
pounds  of  solution  is  about  the  proper  strength. 
Rennet-extract  properly  prepared  is  dark  in  color,  but 
clear.  The  appearance  of  turbidity  in  the  extract  is 
an  indication  of  the  beginning  of  decomposition.  It 
must  be  kept  in  a  cool,  dark  place.  In  some  cases, 
whey  was  once  used  as  a  medium  for  preparing  ren- 
net-extract, a  practice  that  would  insure  a  large  nurn- 
ber  of  objectionable  micro-organisms  in  the  extract. 
It  can  readily  be  seen  how  home-made  rennet-extract 
may  be  a  source  of  serious  bacterial  contamination 
in  milk.  The  preparation  of  home-made  extracts  is, 
fortunately,  much  less  common  now.  The  serious 
objections  to  their  use  are  (i)  liability  to  bacterial 
contamination  and  (2)  variation  in  strength  of  dif- 
ferent lots,  usually  requiring  the  use  of  quite  variable 
amounts  of  one  preparation  as  compared  with  another. 
Commercial  rennet-extract. — The  general  substi- 
tution of  commercial  for  home-made  rennet-extracts 
is  of  distinct  advantage  in  cheese-making,  because  the 
commercial  forms  are  much  more  uniform  in  strength 
and  less  liable  to  bacterial  contamination.  Commer- 
cial rennet-extracts  contain  about  16  per  cent  of  salt 
and  a  trace  of  boric  acid.  Some  have  expressed  the 
fear  that  the  boric  acid  used  as  a  preservative  in  ren- 
net-extract might  injure  the  value  of  cheese  as  a  pure 
food.  There  need  be  absolutely  no  alarm  felt,  when 
we  consider  the  small  amount  of  rennet-extract  used 
in  cheese-making  and  the  very  small  proportion  of 
this  that  goes  into  cheese.  In  fact,  the  amount  of 


302     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

boric  acid  introduced  into  cheese  through  the  rennet- 
extract  is  too  small  to  identify  by  delicate  chemical 
tests.  Commercial  rennet-extracts  vary  in  strength 
and  new  lots  always  need  testing  before  being  used 

(P- 430). 

Strength  of  rennet-enzym  in  coagulating  milk- 
casein. — How  powerful  the  action  of  rennet-enzym 
is  in  coagulating  milk-casein  can  be  seen  in  cheese- 
making,  where  we  use  only  about  one  part  of  rennet- 
extract  for  4,000  or  5,000  parts  of  milk,  and  it  must 
be  kept  in  mind  that  rennet-extract  is  only  a  dilute 
form  of  the  rennet-enzym.  It  has  been  estimated  that 
one  part  of  pure  rennet-enzym  can  coagulate  three 
million  parts  of  milk.  Apparently,  rennet-extract 
does  not  exhaust  itself  by  its  own  action,  a  general 
characteristic  of  enzyms,  but  can  be  repeatedly  used; 
at  least  this  is  theoretically  true.  For  example,  if  we 
could  recover  from  whey  and  curd  the  rennet  used 
in  coagulating  milk,  it  would  coagulate  an  equal  quan- 
tity again.  As  stated  already,  one  of  the  most  char- 
acteristic properties  of  an  enzym  is  that  it  can  produce 
very  powerful  effects  without  itself  being  affected  in 
any  way. 

Explanation  of  the  coagulating  action  of  rennet- 
enzym.— A  large  amount  of  effort  has  been  devoted 
to  the  study  of  the  coagulating  effect  of  rennet-enzym 
in  order  to  ascertain  just  what  the  rennet  does  to  the 
milk-casein  to  make  it  coagulate.  Many  different  ex- 
planations have  been  offered,  but  in  the  present  state 
of  our  knowledge  it  is  impossible  to  give  an  explana- 
tion of  the  process  that  can  be  regarded  as  satisfac- 
tory and  conclusive.  The  most  we  can  do  here  to 
advantage  is  to  present  the  details  of  the  process,  so 


MICRO-ORGANISMS   AND   ENZYMS  303 

far  as  they  appear,  to  be  worked  out.  The  rennet 
coagulation  of  milk-casein  is  believed  to  take  place 
in  three  quite  distinct  stages  or  phases,  as  follows: 
(i)  Change  of  casein  into  paracasein;  (2)  change 
of  the  calcium  salts  of  the  milk  into  soluble  form ; 
and  (3)  precipitation  of  uncoagulated  paracasein  by 
the  soluble  calcium  salts. 

( i )  First  stage  of  rennet  action;  change  of  casein 
into  paracasein. — The  change  of  casein  into  paracasein 
is  wholly  dependent  on  the  action  of  rennet-enzym. 
There  is  no  change  visible  to  the  eye,  neither  increase 
of  consistency  (viscosity)  nor  any  apparent  coagula- 
tion. In  the  absence  of  soluble  calcium  salts,  the 
paracasein  that  has  been  formed  remains  in  this  un- 
coagulated condition.  The  action  in  this  stage  of  the 
process  takes  place  as  well  in  the  cold  as  at  higher 
temperatures.  What  evidence  have  we  that  casein  is 
changed  into  paracasein  before  coagulation  takes 
place  ?  This  is  shown  experimentally  as  follows :  To 
a  solution  containing  some  salt  of  casein,  free  from 
soluble  calcium  salts,  we  add  rennet-extract.  No  co- 
agulation takes  place.  This  solution  is  heated  high 
enough  to  destroy  the  power  of  the  rennet  to  a.ct  and 
then  cooled,  after  which  calcium  chlorid  or  some  other 
soluble  calcium  salt  is  added,  when  coagulation  ap- 
pears at  once.  It  may  be  stated  here  that  one  of  the 
most  characteristic  differences  between  milk-casein 
and  paracasein  is  that  soluble  calcium  salts  da  not 
coagulate  milk-casein  at  ordinary  temperatures,  but 
they  do  cause  coagulation  of  paracasein.  In  the  fore- 
going experiment,  rennet  does  something  to  the  casein 
compound  which  causes  the  casein*  to  da  what  it  could 
not  do  before,  that  is,  coagulate  at  ordinary  tem- 
peratures by  addition  of  soluble  calcium  salts,  even 


304     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

when    the    rennet-enzym    itself    had    been    removed 
from  the  field  of  action. 

(2)  Second   stage    of   rennet    action;    change    in 
calcium  salts  of  milk. — In  the  second  stage  of  rennet 
action,  it  is  believed  that  the  rennet-enzym  acts  upon 
the   insoluble   calcium    salts   of   the .  milk,   converting 
them  into  a  form  sufficiently  soluble  to  enable  them  to 
coagulate  the  paracasein.     This  action  appears  to  take 
place  more  slowly  than  does  the  conversion  of  casein 
into  paracasein.      This  accounts  for  the  period  of  time 
that  elapses  between  addition  of  rennet  and  coagula- 
tion ;  this  time  can  be  shortened  by  addition  of  soluble 
calcium  salts. 

(3)  Third  stage  of  rennet  action;  precipitation  of 
uncoagulated    paracasein. — During    this    period,    in- 
creased viscosity  (thickening)  and  visible  coagulation 
take  place.      This  change,   it  is  generally  agreed,  is 
caused  by  the  action,  either  physical  or  chemical,  of 
soluble  calcium  salts  upon  the  uncoagulated  paracasein 
formed  during  the  first  stage  of  the  process.     After 
the  second  stage  is  completed  or  nearly  so,  coagulation 
commences    and   proceeds    rapidly.      The    paracasein 
coagulum  (curd)  formed  in  milk  always  contains  in- 
soluble calcium  phosphate,  which  is  probably  held  in 
a  purely  mechanical  way,  although  some  believe  that 
it  is  in  combination  with  paracasein. 

What  is  the  evidence  leading  us  to  believe  that  a 
soluble  calcium  salt  is  necessary  for  the  coagulation  of 
milk-casein  ?  Two  lines  of  experimental  evidence  have 
been  furnished,  (ist)  If  we  prepare  a  pure  solution 
of  neutral  calcium  casein  or  sodium  casein,  contain- 
ing no  soluble  calcium  salts,  rennet-extract  will  not 
coagulate  such  a  solution,  but,  after  the  addition  of 
some  soluble  calcium  salt,  as  calcium  chlorid,  coagula- 
tion takes  place  promptly.  (2nd)  Milk  from  which 


MICRO-ORGANISMS    AND    ENZYMS  305 

the  soluble  calcium  salts  have  been  removed  by  pre- 
cipitation with  ammonium  oxalate  or  by  dialysis  is 
not  coagulated  by  rennet-enzym  until  a  soluble  cal- 
cium salt  is  added.  We  may,  therefore,  summarize 
as  follows  what  appears  to  be  fairly  well  established 
in  explanation  of  the  coagulating  action  of  rennet: 

(1)  That  milk-casein  is  the  only  substance  in  milk 
involved   in  the  rennet  coagulation,   excepting  phos- 
phates of  calcium  and  other  soluble  salts  of  calcium. 

(2)  That  in  rennet  coagulation,  no  change  of  reaction 
or  acidity  occurs ;   the  milk  becomes  neither  acid  nor 
alkaline  through  rennet  action.      (3)     That  the  two 
active  agents  in  the  rennet  coagulation  of  milk  are 
rennet-enzym  and  soluble  calcium  salts. 

Relation  of  casein  and  paracasein. — In  the  fore- 
going discussion  of  the  process  of  rennet  coagula- 
tion, there  is  nothing  to  indicate  just  what  happens 
to  milk-casein  in  being  changed  into  paracasein, 
or,  in  other  words,  just  how  paracasein  really  dif- 
fers from  milk-casein.  It  must  be  confessed  that 
we  do  not  know  at  all  clearly,  although  there  are 
many  suggestions.  We  know  only  this  with  cer- 
tainty, that  milk-casein  does  not  readily  coagulate 
in  the  presence  of  dilute  calcium  salts  at  ordinary 
temperatures,  but  paracasein  does.  Otherwise  the 
general  properties  of  casein  and  paracasein  are 
very  similar.  Some  hold  that  the  difference  is 
purely  physical,  the  paracasein  consisting  of  larger 
particles  than  the  casein.  While  the  ultramicro- 
scopic  study  (p.  143)  of  rennet  coagulation  enabled 
the  observers  to  see  the  minute  particles  of  casein 
come  together  and  form  larger  aggregations  under  the 
action  of  rennet,  this  does  not  show  whether  this 


306     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

physical  change  was  accompanied  by  any  chemical 
change  in  the  milk-casein. 

Dissolving  or  digesting  action  of  rennet-enzym. — 
Rennet-extract  has  the  power  of  dissolving  paracasein, 
this  peptic  action  being  slow  but  continuing  for  a  long 
time  in  cheese.  Whether  one  enzym  does  both  the 
coagulating  and  the  digesting,  or  whether  there  are 
two  specific  enzyms  (rennin  and  pepsin),  each  per- 
forming its  special  kind  of  work,  is  not  fully  settled, 
but,  as  already  stated,  the  results  of  most  recent  in- 
vestigations point  to  two  distinct  enzyms-. 

Conditions  of  action  of  rennet-enzym. — The  con- 
ditions under  which  rennet-enzym  coagulates  milk- 
casein  have  been  extensively  studied  and  we  will  now 
consider  some  of  the  more  important  ones.  The 
rapidity  and  completeness  of  coagulation  of  milk- 
casein  by  rennet-enzym  are  dependent  upon  the  fol- 
lowing conditions : 

1 I )  The  presence  of  soluble  calcium  salts  appears 
to  be  necessary  for  the  coagulation  of  milk-casein  by 
rennet-enzym.     This  has  been  discussed  already. 

(2)  Effect  of  acids. — Milk  must  be  neutral  or  acid 
in  reaction  in  order  to  be  coagulated  by  rennet-enzym. 
Free  acids  or  acid  salts  favor  the  action.     All  acids, 
whether  organic  or  inorganic,  show  very  marked  effect 
upon  the  coagulation,  though  they  differ  from  one 
another  in  respect  to  the  extent  of  influence  which 
they  exert  on  rennet  action.     The  more  acid  there  is 
in  the  milk,  up  to  a  certain  limit,  the  more  quickly  does 
coagulation  by  rennet-enzym  take  place.     Milk  sour 
enough  to  curdle  is  not  coagulated  by  rennet;    sim- 
ilarly, sour  buttermilk  is  not  coagulated.     The  follow- 
ing table  shows  the  results  of  some  work  done  at  the 


MICRO-ORGANISMS    AND    ENZYM8 


307 


New  York  experiment  station  on  this  subject.  The 
experiments  were  made  by  treating  350  cubic  centi- 
meters of  fresh  milk  at  84°  F.  with  i.o  cubic 
centimeter  of  rennet  solution,  made  by  dissolving  one 
of  Hansen's  rennet-tablets  in  150  cubic  centimeters  of 
distilled  water. 


Acids  used 

Original 
milk 
coagulated 
in 
seconds 

Strength  of  acid  used 

0.01 

per  cent 

0.02 

per  cent 

0.03 

per  cent 

0.04 

per  cent 

0.05 

per  cent 

Time  of  coagulation  in  seconds 

Acetic 

110 
105 
105 
110 
105 
135 

70 
70 
80 
80 
85 
110 

45 
50 
60 
65 
70 
90 

35 
30 
45 
45 
60 
80 

25 
25 
40 
35 
50 
75 

20 
20 
35 
30 
45 
60 

Sulphuric  
Citric  

Hydrochloric  . 
Phosphoric   .  . 

This  effect  of  acids  upon  rennet  action  is  com- 
monly explained  by  saying  that  the  added  acid  dis- 
solves the  insoluble  calcium  phosphates  of  milk  and 
thus  increases  the  amount  of  soluble  calcium  salts. 
It  is  known  that  even  carbon  dioxid  gas  favors  rennet 
coagulation,  due  to  its  dissolving  action  on  insoluble 
calcium  salts  in  milk. 

(3)  Dilution  of  milk  by  water  both  delays  rennet 
action  and  renders  coagulation  less  complete,  because 
the  proportion  of  soluble  calcium  salts  is  decreased. 
Addition  of  calcium  chlorid  or  free  acid  to-  milk  thus 
diluted  not  only  hastens  the  time  of  coagulation,  but 
makes  more  complete  the  amount  of  milk-casein  co- 
agulated. Apparently,  milk  may  be  diluted  more  than 
10  per  cent  with  water  before  the  time  of  rennet 


308     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


coagulation  is  greatly  affected.       The  effect  of  water 
is  illustrated  in  the  following  table : 


Cubic 

Cubic  centi- 

Percentage of 

Cubic  centi- 

centimeters 

meters  of 

added  water 

meters  of 

Time  of 

of  milk 

water  added 

in  watered 

rennet  solu- 

coagulation 

to  milk 

milk 

tion  used 

Minutes-Seconds 

175 

175 

50 

0.5 

5  —  20 

175 

175 

50 

1.0 

3  —  20 

280 

70 

20 

1.0 

2  —  00 

315 

35 

10 

1.0 

1  —  50 

332* 

m 

5 

1.0 

1  —  45 

350 

0 

0 

1.0 

1  —  30 

(4)  Different  chemical  compounds  and  metals 
affect  the  rennet  coagulation  of  milk  in  different  ways. 
Acid  salts,  in  general,  like  free  acids,  favor  rapidity 
of  coagulation.  Alkalis  and  alkaline  salts  retard  it. 
The  following  substances,  if  present  in  certain 
amounts,  retard  rennet  coagulation  of  milk-casein: 
Sodium  chlorid  (common  salt),  sodium  acetate, 
borax,  chloroform,  formalin  and  some  other  sub- 


strength  of  Compound  Used 


Compound 
used 

Origi- 
nal 
milk 

0.01 
per  cent 

0.05 
per  cent 

0.10 
per  cent 

0.5 
per  cent 

1.0 
per  cent 

2.0 
per  cent 

Number  of  seconds  required  to  coagulate  milk 

Sodium  chlorid 
Sodium  nitrate 
Sodium  bicar- 
bonate   

110 

115 
115 
100 
100 

135 
135 

115 
120 
120 
100 

140 
150 

170 
180 
270 
100 

130 
195 

265 
280 
600 
90 

.130 
300 

115 

(lOcc.) 
150 

120 
150 

(20cc.) 
165 

160 
225 

(30cc.) 
210 

Sodium  acetate 
Borax  
Boracic  acid..  . 
Ammonium 
chlorid  
Ammonium 
carbonate  .  .  . 

Lime-water  .  .  . 

MICRO-ORGANISMS    AND    ENZYMS 


309 


stances,  which  are  used  in  milk  as  preservatives.  The 
foregoing  table  shows  the  results  of  some  work  done 
at  the  New  York  experiment  station  on  this  point. 

It  has  been  shown  at  the  Wisconsin  experiment 
station  that  some  metals  exert  a  retarding  effect  on  the 
coagulating  action  of  rennet.  As  a  practical  applica- 
tion, it  is  pointed  out  that  in  rusty  milk-cans  enough 
iron  may  be  dissolved  by  milk  that  is  at  all  acid  to 
interfere  with  the  rennet  coagulation. 

(5)  Finely   divided,   inert   matter,    like  "starch   or 
sawdust,  added   to  milk,   hastens   the   coagulation  by 
rennet. 

(6)  The  temperature  of  the  milk  affects   (i)  the 
time   of   coagulation,   and    (2)    the   character   of   the 
curd. 

(a)     For    complete    coagulation,    the    time    de- 
creases when  the  temperature  increases. 


Temperature,  F..                 ... 

75° 

80° 

85° 

90° 

95° 

Time   seconds 

270 

140 

110 

80 

65 

Stated  in  another  way,  the  coagulation  in  a  given 
time  is  most  complete  at  106°  to  108°  F.  and  less 
complete  at  temperatures  above  and  below  these 
limits.  Fleischmann  gives  the  following  figures, 
indicating  the  proportion  of  milk-casein  coagulated  in 
the  same  period  of  time  required  to  effect  complete 
coagulation  at  106°  to  108°  F. 

Proportion  of  milk- 
Temperature  casein  coagulated 

68° 18  per  cent 

77° 44  per  cent 

86° 71  per  cent 

95° 86  per  ecnt 

104° 98  per  cent 

106° 100  per  cent 

113°.  89  per  cent 

122° 50  per  cent 


3IO     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

(b)  The    character    of    the    coagulation    is    af- 
fected   by    the    temperature    at    which    the    rennet- 
enzym  acts.     Thus,  at  60°  F.,  the  curd  is  flocculent, 
spongy  and  soft;  at  77°  to  113°  F.,  it  is  more  or  less 
firm  and  solid;  at  122°  and  above,  it  is  very  soft,  loose 
and  inclined  to  be  gelatinous. 

(c)  Milk  heated  above  150°  F.  for  a  consider- 
able length  of  time  coagulates  less  rapidly  than  nor- 
mal   milk.     The    coagulum   of    such    heated    milk   is 
highly  floeculent,  never  a  firm  and  solid  mass,  in  the 
absence    of    soluble    calcium    salts    or    acids.     Boiled 
milk  fails  to  coagulate  normally,  if  at  all,  by  rennet- 
enzym,  unless  treated  with  some  soluble  calcium  salt 
or  some  acid.     The  degree  of  heat  used  decreases  the 
amount  of  soluble  calcium  salts  in  milk  and  also  drives 
out  any  carbon  dioxid  present. 

(7)  Exposure  to  sunlight  weakens  the  coagulating 
power  of  rennet-extract. 

(8)  Solutions   of  rennet-extract  are   affected    b\ 
heat. — Rennet-extract   heated    for    some    time    above 
140°    F.   becomes    permanently    weaker,    or   inactive. 
Rennet-enzym  begins  to  suffer  injury  at  about  120°  F. 
Weak  solutions  are  injuriously  affected   at  tempera- 
tures as  low  as  105°  F.      Strong  solutions  are  weak- 
ened by  heating  at  150°  F.  for  15  minutes,  but  are  not 
entirely  destroyed.      High  temperatures  destroy  the 
activity    of   rennet-enzym   gradually,    not    instantane- 
ously. 

(9)  Increase  in  amount  of  rennet-extract   or   in 
strength  of  rennet-enzym  hastens  coagulating  effect  on 
milk. 

(10)  Milk,    freshly    draivn,    curdles    more    com- 
pletely than  when  allowed  to  cool,  due  to  lowering  of 
temperature  and,   perhaps,  to  the  presence   of  more 


MICRO-ORGANISMS    AND   ENZYMS 


carbon  dioxid.  In  freshly  drawn  milk,  the  proportion 
of  casein  coagulated  decreases  until  the  temperature  of 
the  surrounding  air  is  reached,  when  it  becomes  sta- 
tionary, until  the  formation  of  lactic  acid  causes  in- 
crease in  activity  of  rennet-enzym.  When  fresh  milk 
fails  to  coagulate  with  rennet-extract,  it  is  probably 
slightly  alkaline  or  contains  no  soluble  calcium  salts ; 
that  is,  it  is  abnormal. 

(n)  Different  milks  behave  differently  toward 
rennet-enzym.  This  is  true  not  only  of  milk. from  dif- 
ferent cows,  but  also  of  milk  from  the  same  cow  at 
different  times.  The  following  results  of  work  done 
at  the  New  York  experiment  station  illustrate  this 
statement : 


Time  of  coagulation  and  date  of  testing 

Number 
of  cow 

July  9 

July  16 

July  21 

Aug.  10 

Aug.  21 

Sept.  15 

Sept.25 

Oct.  30 

M.  —  S. 

M.—  S. 

,M  —  S. 

M.—  S. 

M.—  S. 

M.—  S. 

M.—  S. 

M.—  S. 

1 

6—15 

5—00 

5—20 

4—20 

6—45 

8—30 

7—00 

6—00 

2 

3—45 

3—45 

3—45 

4  —  20 

3  —  40 

3—30 

5—00 

4  —  15 

3 

2—15 

2—50 

2—50 

3  —  00 

2  —  45 

2—00 

2—00 

2—00 

4 

2—50 

2—50 

2—30 

2—25 

1  —  50 

3—30 

5 

2—10 

2  —  15 

2  —  05 

2  —  05 

2  —  00 

1—25 

2—00 

2—30 

6 

2—  OO 

2  —  00 

2—05 

2—05 

2—50 

2—45 

2—40 

2—15 

7 

2—05 

1—55 

2—00 

2—05 

1—55 

1—50 

1—55 

1—402 

8 

2—00 

1  —  50 

2—10 

2—30 

4  —  OQi 

3—10 

9 

4—15 

4  —  20 

3—00 

2—40 

3—30 

3^66 

3—45 

2—00 

10 

1—35 

1—50 

2—10 

1—45 

1—25 

1—40 

1—45 



11 

1—35 

1—35 

1—35 

1—35 

1—35 

1—35 

1  —  40 

12 

2—10 

2—00 

2—20 

1—50 

1—55 

1—45 

2—30 

13 

1—05 

1  —  10 

1—10 

1—10 

1  —  05 

1—05 

1—10 

14 

23—00 

16—20 

10—00 

10—00 

29—00 

4  —  45 

50  —  00 

7—66 

15 

0  —  50 

0—45 

0—50 

0—45 

1—00 

0—50 

0—40 

0-r45 

16 

2—05 

2—30 

2—00 

1—55 

3—00 

3—00 

3—10 

17 

1—55 

1—45 

1—55 

2  —  05 

1—40 

1  —  35 

1  —  40 

i—  36 

1  Close  of  lactation  period.          2  Fresh  in  milk. 


These  results  show  that  in  the  individual  milkings 
of  these  17  cows  the  time  of  rennet  coagulation  of 
fresh  milk  varied  from  40  seconds  to  50  minutes.  In 


312     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

the  case  of  one  individual  (No.  14),  the  variations 
were  from  4  minutes  and  45  seconds  to  50  minutes. 
A  study  of  the  ordinary  composition  of  the  milk  gave 
no  clue  to  the  cause  of  such  differences.  The  specific 
causes  are  not  yet  understood,  but  are  probably  related 
to  the  calcium  salts  in  milk  and  their  solubility. 

PEPSIN-ENZYM 

The  chief  enzym  of  the  gastric  juice  in  the  stomach 
of  man  is  known  as  pepsin.  The  same  enzym  is  also 
present  in  the  stomach  of  many  animals.  A  prepara- 
tion made  from  the  stomachs  of  sheep  is  on  the 
market,  which  may  be  successfully  used  as  a  sub- 
stitute for  rennet-extract  in  cheese-making.  This 
has  the  property  of  both  coagulating  and  digesting 
milk-casein.  The  pepsin  most  experimented  with 
has  been  the  scale  pepsin  of  Armour  &  Co.  This 
pepsin  does  not  coagulate  very  sweet  milk  as  read- 
ily as  rennet-extract,  but  in  milk  having  an  acidity 
of  0.20  per  cent,  it  acts  just  as  Well,  when  used  in 
the  proportion  of  5  grams  for  1,000  pounds  of 
milk.  The  pepsin  is  dissolved  in  any  convenient 
amount  of  water  before  addition  to  milk.  The 
solution  should  be  prepared  fresh  for  each  day's  use. 
The  complete  identity  of  rennet-enzym  and  pepsin  is 
not  fully  settled.  Assuming  that  the  coagulating 
effect  of  these  preparations  is  due  to  one  enzym 
(rennin)  and  the  digesting  effect  to  another  (pepsin), 
the  various  preparations  differ  in  respect  to  the 
amounts  of  these  two  enzyms  which  they  contain. 
Rennet-extracts  contain  more  rennin  and  less  pepsin, 
while  the  commercial  preparations  made  from  the 
stomachs  of  pigs  and  sheep  appear  to  contain  more 
pepsin  and  less  rennin. 


CHAPTER  XXIII 

The  Ripening  of  Cheese 

It  is  well  known  that  cheddar  cheese  must  have  age 
before  it  is  edible.  When  taken  from  the  press,  cheese 
is  said  to  be  unripe,  green,  or  uncured.  At  this  time, 
it  has  no  real  cheese  flavor,  and  little  flavor  of  any 
kind.  Its  body  is  very  firm,  somewhat  tough,  rather 
elastic,  and  rubber-like.  Its  proteins  are  only  slightly 
soluble  in  water.  It  is  not  palatable  and  requires  much 
mastication  before  it  can  be  swallowed  comfortably. 
Green  cheese  gradually  undergoes  very  marked 
changes  in  the  course  of  some  weeks  or  months,  the 
time  required  depending  upon  a  variety  of  conditions. 
The  cheese  finally  becomes  mellow  in  body  and  ac- 
quires richness  of  taste  and  a  characteristic  delicacy  of 
flavor.  It  is  highly  palatable  and,  when  a  piece  is 
held  on  the  tongue  a  short  time,  the  cheese  dissolves, 
giving  a  sensation  of  smoothness  and  richness.  The 
casein-derived  proteins,  which  are  insoluble  as  found 
in  the  curd  and  green  cheese,  become  soluble  to  a 
large  extent.  The  process,  by  which  the  qualities  of 
the  newly  made  cheese  are  so  profoundly  changed 
and  as  a  result  of  which  the  product  becomes  edible, 
is  known  as  ripening  or,  less  aptly,  as  curing. 

For  a  long  time  the  importance  of  caring  for  cheese 
after  it  leaves  the  press  was  not  appreciated,  and  not 
until  within  about  15  years  has  much  attention  been 
given  to  methods  of  cheese-ripening  in  this  country. 
The  rule  has  been  and  still  is,  in  too  many  cases,  to 

313 


314     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

place  the  cheese  in  some  room  in  the  factory  where 
are  provided  no  means  of  controlling  temperature  and 
moisture  and  where  the  variations  in  these  factors 
closely  follow,  up  and  down,  the  conditions  existing 
out  of  doors.  It  has  come  to  be  realized  that  a  cheese, 
perfect  when  it  leaves  the  press,  may  easily  be  ruined 
for  market  by  lack  of  care  during  the  ripening  process. 
It  is  appreciated  now  more  than  ever  before  that  the 
ripening  of  cheese  is  a  part  of  the  manufacturing  proc- 
ess, that  it  is  the'  real  finishing  of  the  product,  and 
must  not  be  slighted  any  more  than  any  other  impor- 
tant step. 

CHANGES    RESULTING    FROM     RIPENING 
PROCESS 

Several  different  changes  take  place  in  cheese  dur- 
ing the  ripening  period.  These  may  be  divided  into 
two  general  classes,  (i)  loss  of  weight  and  (2) 
chemical  changes  in  the  cheese  constituents.  We 
shall  now  take  up  for  consideration  a  somewhat  de- 
tailed study  of  (i)  the  extent  to  which  these 
changes  take  place,  (2)  the  various  conditions  under 
which  they  occur,  (3)  their  relations  to  the  character 
of  the  cheese  and  (4)  the  commercial  relations  of 
cheese-ripening. 

LOSS  OF  WEIGHT  IN  CHEESE-RIPENING 

The  loss  of  weight  in  the  cheese-ripening  process, 
when  the  conditions  are  normal,  may  be  regarded  for 
practical  purposes  as  being  due  entirely  to  the  evapora- 
tion of  water  from  the  cheese.  Of  course,  there  is 
some  mechanical  loss  of  fat  by  exudation  ("leaking") 
from  cheese  kept  at  high  temperatures,  but  such  con- 
ditions are  abnormal.  The  small  amount  of  loss  due 


RIPENING   OF    CHEESE  315 

to  the  formation  and  escape  of  carbon  dioxid  (p. 
334)  and  other  gases  can  be  neglected  for  practical 
purposes. 

CONDITIONS  AFFECTING  LOSS  OF  WATER 
IN  CHEESE-RIPENING 

The  rapidity  and  extent  of  loss  of  moisture  in 
cheese  during  the  process  of  ripening  vary  with  sev- 
eral conditions,  chief  of  which  are  the  following :  ( I ) 
The  temperature  of  the  room,  (2)  the  proportion  of 
water- vapor  present  in  the  air  of  the  room,  (3)  protec- 
tion of  surface  of  cheese,  (4)  size  and  shape  of  the 
cheese,  (5)  the  percentage  of  moisture  originally  pres- 
ent in  the  cheese,  and  (6)  the  texture  of  the  cheese. 
The  data  used  in  illustrating  these  points  are  taken 
largely  from  the  results  of  investigations  carried  on 
at  the  New  York  experiment  station. 

Temperature  and  loss  of  weight. — We  present, 
first,  data  showing  the  influence  of  temperature  upon 
the  loss  of  moisture  at  six  different  temperatures,  viz : 
55°,  60°,  65°,  70°,  75°  and  80°  F. 

The  cheeses  used  in  furnishing  data  in  the  table  on 
page  316  were  15  inches  in  diameter  and  weighed 
about  65  pounds,  the  usual  standard  size  of  the  most 
common  type  of  American  cheddar  cheese  intended 
for  export  trade. 

These  results  show  an  increase  in  loss  of  weight 
with  increase  of  temperature.  As  between  55°  and 
80°  F.,  the  loss  increased  on  an  average  I  ounce  per 
loo  pounds  of  cheese  for  each  additional  degree  of 
temperature  during  the  first  4  weeks;  2  ounces  per 
100  pounds  of  cheese  for  each  degree  during  the  first 
2  months ;  and  3^  ounces  at  the  end  of  3  months. 


3l6     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


LOSS    OF    MOISTURE    AT    DIFFERENT    TEMPERATURES 


Tempera- 

Water  lost  by  100  pounds  of  green  cheese  in 

curing- 

1 

2 

3 

4 

8 

12 

16 

20 

24 

28 

wk. 

wks. 

wks. 

wks. 

wks. 

wks. 

wks. 

wks. 

wks. 

wks. 

Degrees  F. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

55 

1.6 

2.6 

3.2 

3.7 

5.2 

6.1 

6.8 

7.5 

8.1 

8.6 

60 

1.7 

2.8 

3.4 

3.9 

5.5 

6.5 

7.5 

8.5 

9.3 

9.9 

65 

1.9 

3.0 

3.6 

4.1 

5.8 

7.0 

8.2 

9.2 

10.1 

10.5 

70 

2.0 

3.1 

3.7 

4.3 

6.0 

7.8 

9.0 

10.1 

11.1 

12.0 

75 

2.2 

3.3 

4.0 

4.7 

7.2 

9.7 

11.4 

80 

2.4 

3.7 

4.5 

5.2 

8.3 

11.6 

15.5 







The  average  weekly  loss  of  weight  increases  with 
increase  of  temperature.  In  the  following  table,  it 
is  seen  that  the  loss  is  greater  the  first  week  than  in 
any  succeeding  week.  The  loss  usually  decreases 
gradually  as  the  cheese  grows  older;  but  cheese  kept 
at  a  temperature  of  75°  F.  and  above  does  not  follow 
this  general  rule,  since  at  the  higher  temperatures 
there  is  apt  to  be  an  increase  of  loss  of  weight  due  to 
leakage  of  fat  after  the  first  month.  This  is  shown 
in  the  table  below: 


AVERAGE    WEEKLY    LOSS    AT    DIFFERENT    TEMPERATURES 


Average  loss  per  week. 

Temper- 

Water lost  by  100  pounds  of  green  cheese. 

Ibs.total 

ature  of 

loss  for 

curing- 

six 

room 

1st 

2d 

3d 

4th 

2d 

3d 

4th 

5th 

6th 

months 

wk. 

wk. 

wk. 

wk. 

mo. 

mo. 

mo. 

mo. 

mo. 

D^F. 

Ozs. 

25.6 

Ozs. 
16.0 

Ozs. 
9.6 

Ozs. 

8.0 

Ozs. 

6.0 

Ozs. 
3.6 

Ozs. 
2.8 

Ozs. 
2.8 

Ozs. 
2.4 

Lbs. 
8.1 

60 

27.2 

17.6 

9.6 

8.0 

6.4 

4.0 

4.0 

4.0 

3.2 

9.3 

65 

30.4 

17.6 

9.6 

8.0 

6.8 

4.8 

4.8 

4.0 

3.6 

10.1 

70 

32.0 

17.6 

9.6 

9.6 

6.8 

4.8 

4.8 

4.4 

4.0 

11.1 

75 

35.2 

17.6 

10.2 

10.2 

10.0 

10.0 

6.8 







30 

38.4 

20.8 

12.8 

10.2 

12.4 

13.2 

15.6 







RIPENING   OF    CHEESE 


317 


The  comparatively  rapid  loss  of  moisture  during 
the  early  stage  of  ripening  is-  due  to  the  fact  that  the 
cheese  contains  its  highest  amount  of  moisture  when 
new.  In  addition,  the  bandage  is  practically  saturated 
with  water,  which  quickly  evaporates.  Then,  again, 
the  outer  surface  of  the  cheese,  in  drying,  begins  to 
harden,  the  meshes  of  the  cheese-cloth  filling  to  some 
extent  with  dried  matter,  and  this  condition  tends  con- 
stantly more  and  more  to  dimmish  evaporation,  pro- 
vided cracking  is  prevented. 

Moisture  in  air  of  curing-room  and  loss  of 
weight. — The  relative  amount  of  moisture  in  air  or, 
more  properly,  the  degree  of  saturation,  exercises 
a  marked  influence  upon  loss  of  water  in  cheese-ripen- 
ing. To  illustrate  this  influence,  we  give  results  of 
an  experiment  in  which  two  cheeses  made  from  the 
same  milk  were  kept  at  60°  F.  One  cheese  was  kept 
on  a  shelf  in  the  ordinary  manner,  the  air  of  the 
room  containing  from  75  to  80  per  cent  of  all  the 
moisture  it  could  hold  at  60°  F.  The  other  cheese 


LOSS     OF     MOISTURE     IN     CHEESE     KEPT     IN     AIR     COM- 
PLETELY   AND    PARTIALLY    SATURATED    WITH    MOISTURE 


Age  of 
cheese 

In  air  partially  saturated 

In  air  completely  satu- 
rated with  moisture 

Moisture  in 
cheese 

Water  lost  by 
100  pounds  of 
cheese 

Moisture  in 
cheese 

Water  gained 
by  100  pounds 
of  cheese 

2  weeks.  .  .  . 
1  month  .  .  . 
2  months.  . 
6  months.  . 
12  months.  . 
1  5  months  .  . 

Per  cent 
35.99 
35.23 
34.86 
31.87 
26.30 
24.85 

Pounds 

0.76 
1.13 

4.12 
9.69 

11.14 

Per  cent 
35.93 
35.87 
36.01 
37.04 
37.63 
37.85 

Pounds 

0.08 
0.11 
1.70 
1.92 

3l8     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


was  placed  under  a  bell- jar  and  kept  in  an  atmosphere 
completely  saturated  with  moisture.  The  results 
secured  by  this  treatment  are  presented  in  the  table 
on  the  preceding  page. 

The  results  of  this  experiment  are  quite  striking. 
In  the  cheese  kept  in  air  incompletely  saturated  with 
moisture,  there  was  a  steady  loss,  so  that  the  cheese 
which  contained  36  per  cent  of  moisture  at  the  start 
had  rts  moisture  content  decreased  to  less  than  25 
per  cent.  On  the  other  hand,  the  cheese  kept  in  a 
saturated  atmosphere  not  only  lost  no  moisture,  but 
actually  gained  water  by  absorption,  so  that  its  per- 
centage of  water  was  increased  from  about  36  per 
cent  at  the  beginning  to  nearly  38  per  cent  at  the 
close  of  the  experiment.  The  two  cheeses,  which 
contained  the  same  percentage  of  moisture  at  the 
beginning,  were  found  to  differ,  at  the  end  of  15 
months,  13  per  cent  in  moisture,  solely  as  the  result 
of  being  kept  in  air  containing  different  degrees  of 
moisture. 

The  same  fact  is  well  illustrated  in  experiments 
made  at  the  Wisconsin  experiment  station.  A  com- 
parison was  made  of  the  relative  humidity  of  the  air 
in  a  curing-room  with  that  inside  a  closed  cheese- 
box,  in  which  a  cheese  was  kept. 


Temperature 

Relative 
humidity  in 
room 

Relative 
humidity  inside 
cheese-box 

Room  1  
Room  2 

35°-40°  F. 
SO°-5S°  F 

Per  cent 
85-92 
55-75 

Per  cent 
100 
94 

Room  3  

60°-69°  F 

50-70 

84-90 

RIPENING   OF   CHEESE  319 

These  results  indicate  that  the  storage  of  cheese  in 
boxes  in  curing-rooms  is  one  means  of  avoiding  the 
results  of  too  rapid  loss  of  ntoisture.  Of  course,  dif- 
ficulty arises  in  the  way  of  molds  in  the  case  of  cheese 
so  stored,  unless  they  are  properly  fumigated  (p. 
134)  or  covered  with  paraffin,  a  point  which  will  be 
considered  next. 

Protection  of  surface  of  cheese  and  loss  of 
weight. — The  covering  of  the  outer  surface  of 
cheese  with  a  layer  of  paraffin  has  been  found  to 
diminish  greatly  the  loss  of  weight.  The  first  sugges- 
tion of  the  practical  use  of  paraffin  in  connection 
with  covering  cheese  came,  so  far  as  we  know,  from 
the  Standard  Oil  Company  about  10  or  12  years 
ago,  when  it  advertised  a  preparation  of  yellow- 
colored  paraffin  for  use  in  protecting  cheese  from 
mold.  Some  experiments  were  made  at  the  Wis- 
consin experiment  station  in  1899  to  prevent  mold 
by  the  use  of  paraffin,  but  the  results  were  not  re- 
garded as  sufficiently  satisfactory  in  every  way  to 
justify  its  recommendation  for  general  use.  In  ex- 
perimental work  at  the  New  York  experiment 
station,  cheese  was  covered '  with  paraffin  in  order 
to  control  moisture,  without  any  reference  to  the 
thought  of  practical  application.  The  matter  was 
later  taken  up  in  a  practical  way  here  and  in  Can- 
ada. The  results  of  co-operative  work  between 
the  United  States  Department  of  Agriculture  and  the 
experiment  stations  of  Wisconsin  and  New  York, 
carried  on  in  1902-3,  may  be  regarded  as  the  first 
demonstration  in  the  United  States  that  attracted 
serious  attention.  Since  then  the  practice  has  grown 


32O     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

rapidly,  but  the  primary  object  is  quite  as  much  pre- 
vention of  loss  of  weight  as  protection  from  mold. 
The  results  of  the  work  done  at  that  time  in  New 
York  will  suffice  as  a  basis  of  discussion.  Cheeses 
weighing  70  pounds  were  used,  some  being  covered 
with  paraffin,  while  others  were  left  in  the  usual  con- 
dition. The  results  are  given  as  follows: 


Cheese 

Age 

Pounds  lost  for  100  pounds  of  cheese 

Kept  at 
40°F. 

Kept  at 
50°F. 

Kept  at 
60°F. 

Normal  

Weeks 
17 
17 
25 
25 
32 
32 

2.5 
0.3 
3.1 
0.6 
4.5 
0.9 

2.4 
0.5 
4.0 
0.9 

4.2 
1.4 

Paraffined  
Normal 

Paraffined  

Normal           .          .... 

Paraffined 

By  covering  cheese  with  paraffin,  a  saving  in  loss 
of  moisture  can  be  effected,  amounting  to  5  or  6 
pounds  per  100  pounds  of  cheese  at  60°  F. ;  while  at 
50°  F.,  and  below,  the  total  loss  of  moisture  can  be 
reduced  to  less  than  I  pound  per  100  pounds  of  cheese. 
In  every  case,  cheeses  covered  with  paraffin  were 
entirely  clean,  while  the  others  were  more  or  less 
heavily  coated  with  molds.  The  saving  effected  by 
paraffining  small-sized  cheeses  is  even  greater  than 
with  those  of  larger  size. 

Size  and  shape  of  cheese  in  relation  to  loss  of 
weight. — The  amount  of  external  surface  is  greater 
in  relation  to  weight  in  the  case  of  a  small  cheese  than 
of  a  larger  cheese,  and  we  should,  therefore,  expect 
a  larger  loss  of  moisture. 


RIPENING    OF    CHEESE 


321 


The  following  table  illustrates  the  losses  of  weight 
in  the  case  of  cheeses  7  inches  in  diameter;  this  is 
the  type  commonly  known  as  "Young  America." 
They  were  made  from  one  vat  of  milk  and  kept 
at  65°  R 

WEIGHT    LOST    BY    CHEESES    OF    VARYING    HEIGHT    AND 
UNIFORM    DIAMETER 


Height 

Weight 

Water  lost  by  100  pounds  of  green  cheese  in 

of 

of 

cheese 

green 

1 

2 

3 

4 

8 

12 

16 

20 

24 

cheese 

wk. 

wks. 

wks. 

wks. 

wks. 

wks. 

wks. 

wks. 

wks. 

Inches 

Pounds 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

3 

4.6 

3.4 

5.3 

6.4 

7.0 

10.7 

12.9 

13.9 

15.9 

17.0 

4 

6.1 

3.3 

5.1 

6.1 

6.7 

9.7 

11.5 

13.0 

14.0 

15.6 

5 

7.9 

2.8 

4.2 

5.5 

6.3 

8.3 

9.8 

11.2 

12.6 

13.4 

6 

9.3 

2.5 

3.9 

5.2 

60 

7.8 

9.4 

10.6 

11.6 

12.8 

7 

11.0 

2.3 

3.4 

4.7 

5.6 

7.4 

8.9 

10.5 

11.2 

12.4 

The  loss  of  weight  decreases  with  increase  in  height. 
Taking  the  total  loss  of  weight  for  different  periods 
of  time,  it  is  seen  that  an  increase  of  one  inch  in  height 
reduced  the  loss  of  weight  per  100  pounds  of  cheese  5 
ounces  at  the  end  of  4  weeks,  13  ounces  at  8  weeks, 
16  ounces  at  12  weeks  and  18  ounces  at  20  weeks. 

In  the  table  on  the  next  page  we  show  the  loss  of 
weight  in  the  case  of  cheeses  having  different  diameters 
and  kept  at  temperatures  ranging  from  55°  to  80°  F. 
It  is  seen  that,  in  general,  the  loss  of  weight  increases 
at  all  temperatures  as  the  diameter  increases,  the  dif- 
ference being  greater  at  higher  temperatures. 

Variation  of  loss  of  moisture  with  different  kinds 
of  cheese. — In  making  small  cheeses  like  "Young 
Americas,"  and  smaller  sizes  (p.  44)  the  propor- 
tion of  loss  is  much  greater,  and  herrce  the  demand 


322     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


WEIGHT    LOST    BY    CHEESES   OF   VARYING   DIAMETER   AND 
UNIFORM    HEIGHT 


Tern 

Water  lost  by  100  pounds  of  cheese 

Weight 

pera- 

Diam- 

of 

ture 

I 

eter  of 

green 

of 

1 

2 

4 

8          12 

16 

20 

24 

cheese 

cheese 

ciiring- 

\vk. 

wks. 

wks. 

wks. 

wks. 

wks. 

wks. 

wks. 

roorns 

Inches  |    Lbs. 

Deg.F. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

15 

65 

80 

2.4 

3.7 

5.2 

8.3 

11.6 

15.5 

7 

9 

80 

3.6 

5.2 

7.3 

10.9 

12.7 

14.5 

16.3 

iV.  i 

IS 

65 

75 

2.2 

3.3 

4.7 

7.2 

9.7 

11.4 

7 

9 

75 

3.1 

4.8 

6.6 

9.2 

11.1 

12.7 

14.1 

is'.i 

IS 

65 

70 

2.0 

3.1 

4.3 

6.0 

7.8 

9.0 

10.1 

11.1 

11 

23 

70 

3.0 

4.2 

6.1 

7.7 

9.2 

10.6 

11.6 

12.4 

7 

9 

70 

2.9 

4.5 

6.2 

8.9    ,  10.9 

12.2 

13.9 

14.6 

IS 

65 

65          1.9 

3.0 

4.1 

5.8  ;    7.0 

8.2 

9.2 

10.1 

13 

31 

65 

2.0 

3.4 

5.1 

6.2 

7.7 

8.7 

9.3 

10.2 

11 

22 

65 

2.6 

3.7 

5.3 

6.9 

8.1 

9.5 

10.4 

11.3 

7 

9 

65 

2.5 

3.9 

5.6 

7.9 

9.5 

10.9 

12.1 

13.1 

IS 

65 

60 

1.7 

2.8 

3.9 

5.5 

6.5 

7.5 

8.5 

9.3 

13 

31 

60 

1.7 

2.7 

4.3 

6.1 

7.3 

8.4 

9.5 

11 

22 

60 

1.9 

3.6 

4.5 

6.3 

7.5 

8.7 

9.6 

ib'.s 

7 

9 

60 

2.4 

3.7 

5.5 

7.7 

9.3 

10.6 

11.9 

12.8 

IS 

65 

55 

1.6 

2.6 

3.7 

5.2 

6.1 

6.8 

7.5 

8.1 

13 

29 

55 

1.5       2.7 

4.2 

5.7 

7.2 

7.9 

8.9 

9.4 

11 

20 

55 

2.1 

3.6 

4.6 

6.4 

7.4 

8.8 

9.4 

10.1 

7 

9 

55 

2.2 

3.6 

5.1 

7.2 

8.8 

9.8 

11.0 

12.0 

is  still  more  imperative  that  these  shall  be  cured 
under  conditions  where  the  loss  of  moisture  shall 
be  greatly  reduced.  This  applies  also  to  such 
sizes  as  "Flats"  and  "Twins."  It  is  not  surprising 
that  the  manufacture  of  small  cheeses  of  the  ched- 
dar  type  has  been  discouraged.  Even  at  the 
higher  prices  they  bring,  the  extra  loss  of  moisture 
and  additional  cost  of  manufacture  are  not  satisfac- 
torily covered.  In  the  manufacture  of  small,  fancy 
kinds  of  soft  cheese,  these  statements  do  not  apply, 
because  an  essential  part  of  the  equipment  consists  of 


RIPENING  OF   CHEESE 


323 


curing-cellars   of    fairly   low    temperature   and   high 
moisture  content. 
Percentage  of  moisture   in   cheese   and   loss   of 

weight. — Below  are  given  results  obtained  with 
cheese  made  so  as  to  contain  water  varying  from  35 
to  55  per  cent  when  taken  from  press. 


LOSS  OF   MOISTURE  IN  CHEESES  CONTAINING  DIFFERENT 
PERCENTAGES    OF    WATER 


Water  in  100 
pounds  of  green 
cheese 

Water  lost  by  100  pounds  of  green  cheese 

In  1  week 

In  2  weeks 

In  3  weeks 

In  4  weeks 

Pounds 
55 
50 
45 
35 

Pounds 
9.0 
5.5 
4.5 
3.3 

Pounds 
11.2 
9.2 
6.3 
4.2 

Pounds 
12.3 
11.0 
8.0 
4.9 

Pounds 
16.8 
12.9 
9.5 
5.7 

These  results  show  that  the  more  moist  a  cheese 
is  when  made,  the  greater  is  the  proportion  of  water 
lost  by  evaporation;  and,  hence,  the  moisture  in  the 
different  cheeses  tends  to  become  more  nearly  alike 
than  at  the  start.  Thus,  cheese  containing  55  per 
cent  of  moisture  lost  about  three  times  as  much  weight 
as  did  the  cheese  containing  35  per  cent  of  water  and 
nearly  twice  as  much  as  the  one  with  45  per  cent. 
Even  when  cheeses  do  not  differ  so  widely  in  water 
content  as  those  above,  the  same  general  rule  holds 
good,  other  conditions,  of  course,  being  the  same. 


Pounds  of  water  in  1  00  pounds  of  green  cheese  .  . 
Pounds  of  water  lost  by  100  pounds  of  green 

41.7 
5.3 

38.7 
4.6 

37.6 
4.5 

35.4 
4.2 

324     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

Texture  of  cheese  and  loss  of  moisture. — Cheese 
filled  with  holes  will  occupy  more  volume  than  the 
same  weight  of  cheese  free  from  holes.  Hence,  cheese 
with  such  faulty  texture  has  a  larger  surface  exposed 
for  evaporation  relative  to  its  weight  and  will  lose 

RIPENED    AT    40°F 


RIPENED  AT   60*F 

FIG.    45 — SECTIONS    OF   TWO   CHEESES    RIPENED    AT    DIFFERENT 
TEMPERATURES.      CLOSE-TEXTURED,    CHEDDAR    TYPE 

more  moisture.  Then,  in  addition,  the  presence  of 
numerous  holes  in  cheese  greatly  facilitates  the  escape 
of  moisture  from  the  interior  of  the  cheese  to  the  sur- 
face. This  is  a  partial  explanation  of  the  fact  that 
cheese  high  in  moisture  loses  water  more  rapidly 


RIPENING    OF    CHEESE 


325 


than  cheese  containing  less  moisture.  It  is  well 
known  that  cheese  containing  high  percentages  of 
water  usually  develops  holes  abundantly,  especially 
when  cured  at  or  above  ordinary  temperatures. 

These  statements  are  effectively  illustrated  in  the 
experiments  carried  on  at  the  Wisconsin  experiment 
station;  results  are  given  for  two  distinct  types  of 
cheese,  which  were  used  in  studying  the  effects  of 
temperature  during  ripening:  (i)  Close-textured, 

RIPENED  AT  40°F 


RIPENED  AT   60°F 

FIG.     46 — SECTIONS    OF   TWO   CHEESES     RIPENED     AT    DIFFERENT 
TEMPERATURES.      SWEET-CURD  TYPE 


326     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

firm-bodied,  long-keeping  type,  suitable  for  export 
trade,  typical  Wisconsin  cheddars.  (2)  Sweet-curd 
type,  as  represented  by  Iowa  and  Illinois  methods  of 
manufacture.  In  connection  with  the  table  below, 
study  Figs.  45  and  46. 

The    following   table   gives   the   results   in    loss   of 
moisture  in  the  cases  of  these  two  types  of  cheese : 


LOSS   OF    MOISTURE 


Age 
when 
ex- 
amined 

Type  1 
(cheddar) 

Type  2 
(sweet-curd) 

Type  1 
(cheddar) 

Type  2 
(sweet-curd) 

27  cheeses 
kept  at  40°F. 

9  cheeses 
kept  at  40°F. 

9  cheeses 
kept  at  60°F. 

5  cheeses 
kept  at  60°F. 

Days 
10 
20 
30 
60 
90 

Per  cent 
0.38 
0.44 
0.58 
0.83 
1.00 

Per  cent 
0.69 
0.82 
0.96 
1.15 
1.42 

Per  cent 
0.96 
1.74 
2.05 
2.95 
3.57 

Per  cent 
1.05 
1.77 
2.29 
3.67 
4.47 

CHAPTER  XXIV 

Chemical  Changes  in  Cheese-Ripening 

In  studying  the  chemical  changes  which  take  place 
during  the  process  of  cheese-ripening,  it  will  be  an 
advantage  to  consider  the  subject  under  the  following 
main  lines  of  inquiry : 

1.  What  chemical  compounds  are  found  in  unripe 
cheese  ? 

2.  What  chemical  changes  do  the  compounds  of 
unripe  cheese  undergo  as  cheese  ripens? 

3.  What    conditions    influence    the    character    and 
extent  of  these  chemical  changes? 

4.  What   causes  the   chemical  changes  of  cheese- 
ripening? 

The  first  three  points  will  be  considered  in  this 
chapter,  the  fourth  being  reserved  for  a  separate 
chapter. 

CHEMICAL  COMPOUNDS  IN  UNRIPE 
CHEDDAR  CHEESE 

Starting  with  unripe  cheese  as  it  comes  from  the 
press,  we  find  the  same  chemical  compounds  and 
groups  of  compounds  mentioned  in  connection  with 
the  composition  of  milk,  viz:  (i)  Water,  (2)  pro- 
teins, (3)  fat,  (4)  sugar,  (5)  neutral  and  acid 
salts,  (6)  salt  and  (7)  gases. 

Water. — The  functions,  amounts  and  ripening 
losses  of  water  in  relation  to  cheese  have  already 

327 


328     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

been  considered.  We  shall  later  consider  its  •  rela- 
tion to  the  chemical  changes  in  cheese-ripening. 

Proteins. — In  cheddar  cheese  fresh  from  press, 
there  appear  to  be  different  protein  compounds,  the 
precise  nature  of  which  has  not  yet  been  deter- 
mined. There  have  been  shown  to  be  the  follow- 
ing forms:  (i)  Protein  soluble  in  warm  (122°- 
131°  F.),  5  per  cent  solution  of  sodium  chlorid, 
which,  for  convenience,  we  shall  speak  of  as  brine- 
soluble  protein,  (2)  protein  insoluble  in  brine  solu- 
tion, and  (3)  proteins  soluble  in  water.  The  first 
constitutes  the  largest  amount,  often  being  75  to 
90  per  cent  of  the  total  amount  of  proteins  in  ched- 
dar cheese ;  the  water-soluble  protein  is  quite  fairly 
constant,  varying  usually  between  4  and  5  per  cent 
of  the  total  proteins,  and  a  part  of  this  is  readily 
accounted  for  by  the  milk-albumin  in  the  whey  re- 
tained in  the  cheese. 

Fat. — The  fat  present  in  unripe  cheese  is,  in 
composition  and  physical  condition,  essentially 
milk-fat. 

Milk-sugar. — The  sugar  in  newly  made  cheese  is 
simply  milk-sugar  in  solution  in  the  whey  that  is 
retained  by  the  cheese. 

Neutral  salts  and  acid  salts. — The  most  promi- 
nent neutral  salt  in  unripe  cheese  is  calcium  lactate, 
formed  as  a  result  of  the  lactic  acid  (produced  by 
the  fermentation  of  milk-sugar)  upon  the  insoluble 
calcium  phosphate  originally  present  in  the  milk,  most 
of  which  is  carried  into  the  cheese-curd  and  held 
there.  The  soluble  acid  salts  present  in  largest 
amounts  are  calcium  acid  phosphate  and,  probably, 
citrate. 


CHEMICAL    CHANGES    IN    RIPENING  329 

Salt. — The  unripe  cheese  contains  common  salt 
which  has  been  added  to  the  curd  in  the  operation 
of  cheese-making.  This  is  held  in  solution,  really 
constituting  a  weak  brine  containing  about  3  per  cent 
of  salt. 

Gases. — In  normal,  unripe  cheese,  gaseous  prod- 
ucts, except  carbon  dioxid,  are  present  in  only 
minute  amounts,  if  at  all.  In  cheese  made  from 
milk  containing  abnormal  micro-organisms,  there 
may  be  present  such  gases  as  hydrogen,  carbon  di- 
oxid, etc. 

CHEMICAL  CHANGES  IN  COMPOUNDS  OF 
UNRIPE  CHEESE 

We  will  now  take  up  each  division  of  the  com- 
pounds which  we  have  considered  briefly  in  the  pre- 
ceding section  and  notice  some  of  the  changes  which 
they  undergo. 

Water. — So  far  as  we  know,  the  water  in  cheese 
undergoes  no  chemical  change.  It  gradually 
evaporates  from  the  cheese  in  the  form  of  water- 
vapor,  the  rate  of  evaporation  varying  with  condi- 
tions studied  in  the  preceding  chapter. 

Proteins. — Of  all  the  compounds  contained  in 
unripe  cheese,  the  proteins  are  the  ones  that  are 
most  extensively  affected  by  the  chemical  changes 
of  ripening,  because  these  compounds  are  not  only 
the  seat  of  those  changes  but  the  material  itself 
which  undergoes  chemical  changes  more  profound 
and  complex  than  any  other  constituent  of  the 
cheese.  There  have  been  and  still  are  many  diffi- 
culties in  carrying  on  a  study  of  the  chemical 


330     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

changes  in  cheese  proteins  during  ripening,  owing 
largely  (i)  to  a  lack  of  detailed  knowledge  of  the 
compounds  formed  and  (2)  to  need  of  more  perfect 
methods  for  estimating  the  amounts  of  these  com- 
pounds, many  of  which  are  formed  only  in  very  small 
quantities. 

Beginning  with  the  milk-casein  in  the  cheese-vat 
at  the  time  the  rennet  is  added,  we  have,  from  that 
time  on,  a  succession  of  changes  in  the  curd  and 
cheese,  resulting  sooner  or  later  in  the  formation  of 
a  series  of  compounds,  which,  so  far  as  our  present 
knowledge  goes,  appears  in  something  like  the  fol- 
lowing consecutive  order: 

(1)  Calcium   paracasein    (formed    from   the    cal- 
cium   casein    of    milk    by    action    of    rennet).       In- 
soluble in  water  and  in  warm,  5  per  -cent  salt-brine. 

(2)  Protein  soluble  in  warm,  5  per  cent  salt-brine. 
(Figs.  30  and  31,  p.  148.) 

(3)  Protein  insoluble  in  salt-brine,  water,  etc. 

(4)  Proteins  soluble  in  water: 

(a)  A   protein   which   is  precipitable  by  dilute 
hydrochloric  acid,  called  paranuclein. 

(b)  A  protein  substance  coagulated  in  neutral 
solution  at  the  boiling  point  of  water.       This  sub- 
stance appears  to  occur  only  rarely,  except  in  the  case 
of  cheese  ripened  near  freezing  point. 

(c)  Proteases  or  cas eases   (albumoses),  which 
are  proteins  or  pfrotein  derivatives   soluble  in  water, 
not  coagulated  by  heat,  and  usually  precipitated  by 
saturating  their  solutions  with  zinc  sulphate  or  am- 
monium sulphate. 

(d)  Peptones,  protein  derivatives  simpler  than 
the   proteoses,    soluble   in   water,   not   coagulated   by 


CHEMICAL    CHANGES    IX    RIPENING  33! 

heat,  and  not  precipitated  by  saturation  with  zinc 
sulphate  or  ammonium  sulphate;  precipitated  by 
phosphotungstic  acid,  tannic  acid  and  some  other 
reagents. 

(e)  Amino   acids,   the   simplest   protein   deriva- 
tives (except  ammonia). 

(f)  Ammonia. 

It  would  be  beyond  the  scope  of  this  book  to  go 
further  into  the  details  of  the  chemistry  of  these 
compounds,  since  they  are  very  complex  and  require 
a  special  knowledge  of  organic  chemistry  to  under- 
stand. 

The  amounts  of  these  protein-derived  products  vary 
with  many  conditions,  some  of  which  will  be  con- 
sidered later  (p.  337). 

Fat. — There  have  been  numerous  investigations 
made  by  different  workers  to  ascertain  whether  the 
milk-fat  in  cheese  decomposes  during  the  ripening 
process.  The  general  results  of  these  investiga- 
tions show  that  cheese-fat  is  unchanged  milk-fat  and 
that  these  glycerin-acid  compounds  (glycerids)  (p. 
140)  do  not  share  extensively  in  the  ripening  proc- 
ess, especially  in  the  case  of  hard  cheese,  such  as 
cheddar.  In  one  case,  it  was  found  that  from  i.o 
to  7  per  cent  of  the  cheese-fat  had  undergone  some 
decomposition,  the  higher  amounts  occurring  in 
soft  cheese.  One  of  the  early  investigators  (Blon- 
deau)  made  several  analyses  of  Roquefort  cheese 
at  various  ages  and  reported  that  the  proteins  of 
the  unripe  cheese  changed  rapidly  into  fat.  This 
statement,  though  frequently  disproved  later,  has 
not  even  yet  entirely  disappeared  from  physiologi- 
cal literature.  The  conclusions  were  based  upon 


332     SCIENCE   AND    PRACTICE    OF    CHEESE-MAKING 

evident  errors  of  analysis,  which  are  readily  appar- 
ent on  careful  examination.  More  recent  work, 
however,  claims  that  some  organisms  can  change 
casein  into  fatty  acids,  while  this  is  especially 
denied  by  another  investigator.  So  far  as  we  now 
know,  the  matter  appears  to  be  one  mainly  of 
academic  interest,  since  the  change  must  be  insig- 
nificant in  amount,  if  it  occurs  at  all.  In  all  of 
our  extended  work  with  cheese,  we  have  found  no 
evidence  of  an  increase  of  fat  at  the  expense  of 
proteins.  And  no  one  has  yet  reported  an  accumu- 
lation of  fat  in  a  separator  skim-milk  cheese  during 
the  ripening  process,  where  the  conditions  surely 
furnish  enough  protein  material  for  such  a  trans- 
formation. 

There  is,  however,  one  interesting  condition 
under  which  some  fat  appears  to  be  changed,  and 
that  is  in  case  of  cheese  cured  at  low  temperatures, 
when  we  should  ordinarily  least  expect  such 
change.  It  has  been  observed  that,  in  cheese  cured 
near  the  freezing  point  of  water,  small  white  specks 
may  appear.  These  have  been  noticed  at  both  the 
Wisconsin  and  New  York  experiment  stations  as 
well  as  in  Europe.  They  have  been  supposed  by 
some  to  be  salts  of  the  cheese  crystallized  out  in 
little  white  aggregations,  due  to  the  dryness  of  the 
cheese  and  the  low  temperature.  One  investiga- 
tor has  reported  the  spots  as  due  to  the  result  of 
bacterial  action  on  the  fat  in  cheese,  some  of  which 
was  decomposed,  the  decomposed  portions  forming 
the  minute  white  spots.  Recently  some  cheese 
filled  with  these  white  specks  has  been  examined 
at  the  New  York  experiment  station.  The  white 


CHEMICAL   CHANGES    IN    RIPENING  333 

spots  are  about  one-eighth  the  size  of  an  ordinary 
pin-head.  They  are  more  or  less  completely  dis- 
tributed through  the  mass  of  the  cheese,  appearing, 
perhaps,  more  numerous  or,  at  least,  more  promi- 
nent in  the  lines  where  the  pieces  of  curd  are 
cemented  together.  Wherever  there  is  a  mechani- 
cal-hole, its  walls  are  well  covered  and  here  the 
specks  appear  specially  prominent  because  they 
simply  lie  on  the  walls  and  are  not  imbedded  in 
the  body  of  the  cheese.  They  can  be  easily  de- 
tached. When  examined  under  a  magnifying  glass, 
the  small  specks  appear  glistening  white  and  also, 
in  some  cases,  the  edges  of  the  curd  pieces,  where 
they  are  cemented  together,  have  the  same  appear- 
ance, very  closely  resembling  paraffin.  The  specks 
crush  easily,  like  fat.  An  examination  showed  them 
to  contain  calcium,  but  no  phosphoric  acid  or  other 
inorganic  salt  in  appreciable  amounts.  Besides 
calcium,  there  appears  to  be  some  fatty  acid,  so 
that  the  substance  appears  to  be  a  calcium  soap. 
Some  of  the  fat  in  the  cheese  is  probably  decom- 
posed by  bacteria  acting  only  at  low  temperatures 
and  a  reaction  takes  place  between  the  fatty  acid 
set  free  and  the  calcium  salts  of  the  cheese.  The 
flavor  and  other  qualities  of  the  cheese  do  not  ap- 
pear to  be  affected  in  any  appreciable  way. 

Milk-sugar  in  cheese,  under  the  action  of  acid 
organisms,  completely  decomposes,  forming  lactic 
acid  chiefly,  with  small  amounts  of  some  other 
products.  The  sugar  in  fresh  cheese  may  amount  to 
i  or  2  per  cent,  but  it  seems  to  disappear  from  the 
cheese,  for  the  most  part,  in  48  hours  and  completely 
within  two  weeks. 


334     SCIENCE    AND    i'RACTiCE    OF    CHEESE-MAKING 

Neutral  salts  and  acid  salts. — As  already  stated, 
there  rarely  appears  to  be  any  free  acid  in  normal 
cheese.  The  calcium  compounds  (mainly  phos- 
phates and  citrates)  are  sufficient  in  amount  to 
make  use  of  the  lactic  acid  which  is  formed,  as 
previously  explained  (p.  149).  The  same  process 
continues  in  the  unripe  cheese  which  previously 
begins  in  the  milk  and  curd  in  the  cheese-vat.  It 
is  probable  that  in  ripened  cheese  the  ammonia  com- 
bines with  the  acid  salts  to  neutralize  their  acidity 
more  or  less  completely,  because,  in  overripe  cheese, 
we  usually  find  the  reaction  alkaline  instead  of 
acid. 

Salt. — So  far  as  known,  salt  undergoes  no  chemical 
change  in  cheese-ripening.  As  the  water  decreases, 
the  brine  or  whey  of  the  cheese  simply  becomes 
stronger,  as  a  matter  of  course. 

Gases. — In  ripened  cheese,  different  gases  in  dif- 
ferent relative  proportions  have  been  found,  but 
little  work  has  been  done  in  connection  with  ched- 
dar  cheese.  The  amounts  and  kinds  of  gases  un- 
doubtedly vary  according  to  various  conditions, 
depending  primarily  (i)  upon  the  kinds  of  micro- 
organisms introduced  into  the  cheese  through  the 
milk,  and  (2)  upon  the  temperature  at  which 
the  cheese  is  ripened.  The  gases  usually  found  in 
largest  amounts  are  carbon  dioxid  and  hydrogen. 
We  have  found  also  hydrogen  sulphid.  The  dry 
matter  in  cheese  is  slightly  reduced,  owing  to  the 
formation  and  escape  of  gases.  In  one  experiment 
at  the  New  York  experiment  station  having  for  its 
object  a  determination  of  the  rate  and  amount  of 
carbon  dioxid  formed  during  ripening  at  60°  F.  by 


CHEMICAL    CHANGES    IN    RIPENING  335 

cheddar  cheese,  it  was  found  that,  under  normal  con- 
ditions, the  cheese  began  giving  off  carbon  dioxid 
gas  at  the*  start  and  continued  to  do  so  in  increasing 
amounts.  At  the  end  of  two  months,  the  rate  of 
formation  was  still  near  its  highest  and  did  not 
begin  to  drop  markedly  until  after  about  20  weeks. 
Measurable  amounts  of  gas  were  still  coming  from 
the  cheese  at  the  end  of  32  weeks,  when  the  experi- 
ment was  discontinued.  The  total  amount  of  carbon 
dioxid  gas  given  off  during  the  entire  experiment 
was  equal  to  0.5  per  cent  of  the  fresh  cheese,  while, 
at  the  end  of  two  months,  it  amounted  to  only  o.i 
per  cent  of  the  original  weight  of  the  cheese. 

CONDITIONS    OF   CHEESE-RIPENING   AND 
CHEMICAL  CHANGES 

We  have  now  considered  the  kinds  of  chemical 
compounds  present  in  unripe  cheese  and  some  of 
the  chemical  changes  which  these  compounds 
undergo.  It  is  known  that  many  of  these  changes 
take  place  gradually,  some  very  slowly,  but  there 
is  a  more  or  less  definite  progression  of  chemical 
changes.  The  same  cheese  examined  at  intervals 
is  found  to  show  quite  marked  variations  in  the 
character  of  its  proteins  and  protein-derived  com- 
pounds. Cheeses  made  from  the  same  milk  under 
the  same  conditions  of  manufacture  and  subjected 
to  different  conditions  during  the  ripening  process 
show  a  difference  in  chemical  composition.  Also, 
cheeses  manufactured  under  different  conditions 
and  ripened  under  uniform  conditions  may  vary 
in  the  character  of  their  nitrogen  compounds.  It 


336     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

is,  therefore,  important  to  know  something  of  the 
relation  of  various  specific  conditions  to  the  forma- 
tion of  those  products  which  are  used  as  a  measure 
of  the  rate  and  extent  of  cheese-ripening. 

Method  of  measuring  rate  of  cheese-ripening. — 
The  development  of  flavor  and  the  changes  in  body 
characteristic  of  ripening  cheese  may  be  used  as 
indications  of  the  rate  and  extent  of  the  ripening 
process,  but  such  a  method  is  too  crude  for  accu- 
rate work.  Up  to  the  present  time,  the  most  sat- 
isfactory method  has  been  to  determine  the 
amount  of  different  products  derived  from  the  pro- 
teins of  the  unripe  cheese.  From  a  chemical  point 
of  view,  in  which  we  consider  solely  the  chemical 
changes  occurring,  without  reference  to  their  cause, 
cheese-ripening  consists  mainly  of  a  change  of  in- 
soluble proteins  into  water-soluble  forms  that  con- 
sist of  other  and  simpler  protein-derived  com- 
pounds, a  list  of  which  is  given  above  (p.  330). 
Hence,  in  a  ripening  cheese,  we  have  progressively 
increasing  amounts  of  proteins  or  protein-derived 
substances,  and  decreasing  amounts  of  insoluble 
proteins.  Therefore,  as  a  measure  of  the  rate  and 
extent  of  ripening  in  cheese,  we  ascertain  the 
amounts  of  water-soluble  proteins  and  protein-de- 
rived substances  and,  from  these  amounts,  reach 
conclusions  as  to  the  degree  of  ripening  that  has 
taken  place.  In  many  cases,  the  determination  of 
the  amounts  of  water-soluble  and  water-insoluble 
substances  alone  is  sufficient;  while  in  others  it  is 
necessary  to  know  something  in  detail  of  the 
amounts  of  each  of  the  protein-derived  constituents. 
Stating  the  matter  in  a  more  comprehensive  way, 


CHEMICAL    CHANGES    IN    RIPENING 


337 


the  amount  of  water-soluble  proteins  and  protein- 
derived  substances  is  used  as  a  measure  of  the  extent 
of  cheese-ripening,  considered  from  a  chemical  stand- 
point. 

The  special  conditions  to  be  studied  in  relation 
to  their  influence  upon  the  character  and  extent 
of  chemical  changes  in  cheese-ripening  are  the  fol- 
lowing: (i)  Time,  (2)  temperature,  (3)  moisture, 
(4)  size,  (5)  salt,  and  (6)  rennet-enzym.  From  the 
large  number  of  data  accumulated,  we  can  give  only 
enough,  in  somewhat  condensed  form,  to  serve  as 
illustrations  of  the  general  facts  discussed. 

Time  and  cheese-ripening. — Under  all  normal 
conditions  that  influence  cheese-ripening,  we  find 
that,  as  cheese  advances  in  age,  there  is  a  progress- 
ive change  resulting  in  an  increase  of  water-sol- 
uble proteins  and  protein-derived  substances.  The 
effect  of  time  as  a  factor  in  cheese-ripening  is  modi- 
fied by  a  variety  of  conditions,  which  will  be  con- 
sidered later.  For  purpose  of  illustration,  we  give 
below  averages  of  the  results  obtained  under  the 

SHOWING    EFFECT    OF   TIME   ON    CHEESE-RIPENING 


Nitrogen,  expressed  as  percentage  of  nitrogen  in  cheese,  in  form  of: 

Age 
of 
cheese 

Brine- 
soluble 
protein 

Water- 
soluble 
proteins 
and  de- 
rivatives 

Para- 

nuclein 

Case- 
oses 

Pep- 
tones 

Amino 
acids 

Ammo- 
nia 

Months 

i* 

6 
9 
12 
18 

Per  cent 
20.18 
27.26 
27.55 
24.14 
19.04 
12.65 

Per  cent 
21.44 
30.98 
36.15 
43.45 
44.75 
47.25 

Per  cent 
2.06 
4.45 
3.57 
4.02 
3.52 
3.40 

Per  cent 
3.15 
4.56 
4.92 
4.59 
4.16 
3.88 

Per  cent 
3.84 
4.65 
4.22 
3.56 
3.95 
2.57 

Per  cent 
9.88 
14.36 
19.96 
26.53 
28.38 
30.46 

Per  cent 
1.56 
2.45 
3.52 
4.74 
5.41 
6.62 

338     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

various  conditions  employed.  Each  analysis  rep- 
resents the  average  of  the  results  obtained  with  24 
different  cheeses. 

It  is  noticeable  that  all  of  the  soluble  forms  of 
nitrogen  compounds  increase  in  amount;  while 
some  increase  continuously,  like  amino  acids  and 
ammonia,  others  increase  for  some  months  and 
then  decrease,  as  paranuclein,  caseoses,  and  pep- 
tones. Taking  the  total  water-soluble  forms  in  the 
cheese  at  the  end  of  18  months,  we  see  that,  of  the 
total  amount  (47.25  per  cent),  45.4  per  cent  was 
formed  in  the  first  six  weeks,  65.5  per  cent  in  the 
first  3  months,  76.5  per  cent  in  the  first  6  months, 
and  92  per  cent  in  the  first  9  months,  which  is  one-half 
the  entire,  period  covered  by  our  study.  In  gen- 
eral, it  is  seen  that,  under  uniform  conditions,  (l) 
the  formation  of  water-soluble  proteins  and  protein 
derivatives  increases  as  cheese  ages;  (2)  the  rate  of 
formation  of  such  compounds  is  more  rapid  in  the 
early  stages  of  ripening,  steadily  diminishing  with 
a§"eJ  (3)  about  two-thirds  of  these  compounds  are 
formed  in  the  first  3  months  and  over  90  per  cent  in 
the  first  9  months. 

Temperature  and  cheese-ripening. — In  general, 
we  find  in  every  individual  cheese  that  temperature 
exerts  a  marked  influence  upon  the  changes  taking 
place  in  the  proteins.  The  effect  of  temperature 
is,  of  course,  modified  by  other  conditions.  As  il- 
lustrative of  the  effect  of  temperature,  we  give  in 
the  table  following  averages  in  which  each  analysis 
embodies  the  analytical  results  furnished  by  four 
different  cheeses  ripened  at  the  same  temperatures. 


CHEMICAL    CHANGES    IN    RIPENING 


339 


We  consider  also  the  factor  of  time  along  with  that 
of  temperature. 


SHOWING  EFFECT  OF  TEMPERATURE  ON   CHEESE- 
RIPENING 


Tem- 
pera- 
ture of 
curing- 
room 

Form  of 
proteins 
and 
derivatives 

Nitrogen  expressed  as  percentage  of  nitrogen  in  cheese 

H 

mos. 

3 

mos. 

6 

mos. 

9 

mos. 

12 
mos. 

18 

mos. 

De    F 

Percent 

Per  cent  ! 

Per  cent 

Per  cent 

Per  cent 

Percent 

32 

Total  water- 

soluble..  . 

12.80 

18.64        23.06 

32.66 

34.02 

36.75 

55 

20.56 

31.46 

36.09 

43.91 

45.09 

49.40 

60 

N 

23.14 

33.69 

39.97 

46.89 

48.62 

50.16 

70 

" 

29.24 

40.13 

45.50 

50.34 

51.25 

52.67 

32 

Brine- 

soluble 

20.58 

43.14        36.55 

43.00        34.48 

21.37 

55 

33.01 

33.66  ;     35.10 

25.61         19.26 

19.45 

60 

M 

13.89 

18.81         19.94 

16.15         12.32 

9.45 

70 

" 

13.24 

13.45 

18.62 

11.83         10.10 

7.86 

32 

Paranuclein 

1.27 

4.05 

3.44 

4.47          4.15 

4.12 

55 

2.39 

5.34 

4.25 

4.27          3.64 

3.68 

60 

« 

2.54 

2.71 

3.90 

4.23          3.59 

4.73 

70 

2.03 

3.71 

2.68 

3.13          2.45 

2.60 

32 

Caseoses.  .  .  . 

1.05 

2.97 

5.24          4.29 

4.17 

5.06 

55 

4.08 

4.50 

5.03          4.76 

4.73 

4.27 

60 

•« 

3.44 

6.14 

6.03  i        5.07 

3.68 

3.00 

70 

"     .... 

4.07 

4.63 

3.37          4.24 

4.12 

3.20 

32      Peptones   .. 
55 

1.30 
3.90 

2.23          4.53 
4.95          3.99 

4.36 
3.10 

4.53 
3.72 

4.17 
2.84 

60 

«« 

3.33           5.99          4.70 

3.44 

4.03 

1.80 

70 

** 

6.81          5.45          3.67 

3.33 

3.51 

1.50 

32 

55 

Amino^  acids 

4.82 
8.69 

6.36 
14.33 

8.70 
19.55 

17.55  !      18.73 
27.05        29.00 

19.44 
31.66 

60 

•• 

12.16 

14.55 

21.39 

28.84 

31.14 

33.54 

70 

" 

13.86 

22.20 

30.80        32.68 

34.65 

37.19 

32 

Ammonia  .  . 

0.61 

0.61 

1.21           1.91 

2.14 

3.98 

55 

1.50 

2.42 

3.30 

4.69 

5.57 

6.95 

60 

• 

1.67 

2.54 

3.89 

5.43 

6.12 

7.35 

70 

•• 

2.47 

4.22 

5.71 

6.91 

7.49 

8.19 

340     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

Summarizing"  our  results,  we  find  that,  other  con- 
ditions being  uniform,  (i)  the  water-soluble  proteins 
and  derivatives  in  cheese  increase,  on  an  aver- 
age, very  closely  in  proportion  to  increase  of  tem- 
perature; (2)  from  the  average  of  our  results,  there 
is  an  increase  of  0.5  per  cent  of  these  water-soluble 
compounds  for  an  increase  of  one  degree  of  tem- 
perature between  the  limits  of  32°  and  70°  F. ;  (3) 
the  amino  acids  and  ammonia  are  formed  in  the  cheese 
more  abundantly  at  higher  temperatures  and  ac- 
cumulate in  the  cheese,  while  the  other  water-soluble 
compounds  do  not  appear  to  be  regularly  influenced 
by  temperature  in  the  early  stages  of  ripening,  but 
after  some  months  they  decrease  in  quantity  with 
increase  of  temperature. 

Moisture  and  cheese-ripening. — In  order  to  study 
the  effect  of  moisture  in  cheese  upon  the  chemical 
changes  taking  place  in  the  nitrogen  compounds, 
two  sets  of  cheeses  were  made  for  comparison,  4 
different  cheeses  in  each  set  being  made  under 
parallel  conditions.  One  lot  was  covered  with 
melted  paraffin,  in  order  to  retard  the  evaporation 
of  water  from  the  cheese;  the  others  were  left  in 
the  usual  condition.  These  cheeses  were  all  kept 
in  the  same  curing-room  at  a  temperature  of  55° 
F.  In  the  tabulated  results  following,  we  give  the 
averages  obtained  with  the  4  different  cheeses  in  each 
set  of  experiments,  those  that  were  covered  with 
paraffin  being  indicated  as  2,  the  others  as  I. 

The  cheeses  covered  with  paraffin  had  somewhat 
less  water  when  made,  but  the  others  lost  water 
more  rapidly,  so  that  at  the  end  of  3  months  their 
water  content  was  about  the  same.  After  this  the 


CHEMICAL    CHANGES    IN    RIPENING 


341 


SHOWING  EFFECT  OF   MOISTURE  IN   CHEESE  ON   CHEESE- 
RIPENING 


No. 
of 
cheese 

Form  of 
proteins, 
and  de- 
rivatives 

Nitrogen  expressed  as  percentage  of  nitrogen  in  cheese 

H 

mos. 

3 
mos. 

6 
mos. 

9 
mos. 

12 
mos. 

18 
mos. 

1 
2 

Total  water- 
soluble... 

Per  cent 

17.32 
17.14 

Per  cent 

27.09 
27.40 

Percent 

31.76 
36.41 

Per  cent 

39.09 
46.59 

Percent 

39.80 
54.52 

Per  cent 

42.77 
56.76 

1 
2 

Brine-solu- 
ble^ 

24.89 
21.17 

41.59 
30.42 

35.43 
49.29 

28.81 
20.16 

21.70 
9.81 

13.72 
5.30 

1 
2 

Paramiclein 

2.70 
0.87 

5.32 
4.35 

4.77 
4.45 

4.20 
4.89 

3.79 
8.01 

4.10 
7.90 

1 
2 

Caseoses  .  .  . 

2.99 
3.58 

5.80 

3.64 

4.24 
5.38 

4.41 
5.06 

4.19 
4.32 

4.26 
4.70 

1 
2 

Peptones...  . 

2.12 
4.49 

4.09 
4.80 

3.75 
6.19 

3.57 
4.00 

3.97 
4.43 

1.95 
3.20 

1 

2 

Amino  acids 

7.50 
7.22 

9.79 
12.59 

16.00 
17.12 

21.65 
26.03 

22.89 
29.44 

26.73 
29.00 

1 

2 

Ammonia  .  . 

1.34 
0.98 

2.15 
1.99 

3.04 
4.26 

4.17 
6.52 

4.53 
8.27 

5.72 
12.16 

2 

Water  

36.40 
35.96 

35.27 
35.00 

32.41 
33.37 

27.86 
33.24 

28.02 
32.66 

27.75 
32.10 

paraffined  cheese  contained  considerably  more  water, 
the  difference  increasing  with  age,  until  at  the  end 
of  12  months  it  was  over  4.5  pounds  per  100  pounds 
of  cheese. 

A  general  review  of  these  results  indicates  the 
formation  of  larger  amounts  of  water-soluble  nitrogen 
compounds  in  cheese  containing  more  moisture,  other 
conditions  being  uniform. 


342     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


Size  of  cheese  and  ripening. — On  page  320  we 
considered  the  influence  of  size  of  cheese  upon  the 
rapidity  of  evaporation  of  water  from  the  cheese. 
Our  results  show  that  the  percentage  loss  of  mois- 
ture is  always  greater  in  smaller-sized  cheeses. 
This  is  what  might  naturally  be  expected,  since  the 
amount  of  external  surface  exposed  for  evaporation 
is  greater,  relative  to  weight,  in  small  than  in  large 
cheeses.  Hence,  difference  in  size  of  cheese  practi- 

SHOWING   EFFECT   OF    SIZE   OF    CHEESE   ON    CHEESE- 
RIPENING 


W'ght 
ot 
cheese 

Form  of 
proteins 
and  de- 
rivatives 

Nitrogen  expressed  as  percentage  of  nitrogen  in  cheese 

1* 

mos. 

3 
mos. 

6 
mos. 

9 
mos. 

12 
mos. 

18 
mos. 

Lbs. 
10 

30 

Total  water- 
soluble.  .  . 

Per  cent 

17.32 
20.56 

Per  cent 

27.09 
31.46 

Per  cent 

31.76 
36.09 

Per  cent 

39.09 
43.91 

Per  cent 

39.80 
45.09 

Per  cent 

42.77 
49.40 

10 
30 

Brine-solu- 
ble   

24.89 
33.01 

41.59 
33.66 

35.43 
35.10 

28.81 
25.61 

21.70 
19.26 

13.72 
19.45 

10 
30 

Paranuclein 

2.70 
2.39 

5.32 
5.34 

4.77 
4.25 

4.20 
4.27 

3.79 
3.64 

4.10 
3.68 

10 
30 

Caseoses  .  .  . 

2.99 
4.08 

5.80 
4.50 

4.24 
5.03 

4.41 
4.76 

4.19 
4.73 

4.26 
4.27 

10 
30 

Peptones    .  . 

2.12 
3.90 

4.09 
4.95 

3.75 
3.99 

3.57 
3.10 

3.97 
3.72 

1.95 
2.84 

to 

30 

Amino  acids 

7.50 
8.69 

9.79 
14.33 

16.00 
19.55 

21.65 
27.05 

22.89 
29.00 

26.73 
31.66 

10 
30 

Ammonia  .  . 

1.34 
1.50 

2.15 
2.42 

3.04 
3.30 

4.17 
4.69 

4.53 

5.57 

5.72 
6.95 

10 
30 

Water  

36.40 
36.31 

35.27 
35.11 

32.41 
33.46 

27.86 
32.29 

28.02 
31.54 

27.75 
28.56 

CHEMICAL    CHANGES    IN    RIPENING  343 

cally  means  difference  in  rapidity  of  loss  of  mois- 
ture, the  larger  cheese  retaining  its  moisture  con- 
tent longer.  We  should  expect,  then,  to  find  es- 
sentially the  same  differences  of  ripening  in  cheeses 
of  different  size  that  we  find  in  cheeses  having  a  dif- 
ferent moisture  content.  To  make  a  study  of  this 
point,  we  present  on  page  342  some  data  showing,  at 
different  stages  of  ripening,  the  amounts  of  derived 
protein  compounds  found  in  cheeses  weighing  respec- 
tively 30  and  10  pounds,  approximately.  The  data 
represent  averages  of  4  different  lots  of  cheeses 
ripened  at  55°  F. 

An  examination  of  the  table  shows,  in  brief,  that 
the  larger  cheeses  contained  more  moisture  after  the 
early  stages  of  ripening  and  that  there  was  a  more 
rapid  increase  in  the  formation  of  total  water-soluble 
derived  proteins,  especially  of  amino  acids  and  am- 
monia, than  in  the  smaller  cheeses. 

Amount  of  salt  and  cheese-ripening. — It  is  a  fact 
that  has  long  been  observed  by  cheese-makers  that 
increase  of  salt  in  cheese  delays  the  rapidity  with 
which  the  cheese  becomes  marketable,  but,  until 
about  five  years  ago,  no  detailed  chemical  results 
were  published  in  relation  to  the  subject.  In  order 
to  study  the  influence  of  salt  upon  the  ripening 
process  in  cheese  properly  made  and  kept,  there 
were  made,  as  nearly  alike  as  possible,  four  different 
lots  of  cheese  under  normal  conditions.  In  each 
lot  there  were  4  cheeses  weighing  30  pounds  each, 
and  salt  was  added  to  these  in  proportions  varying 
as  follows:  No  salt,  1.5,  2.5,  and  5  pounds  of  salt 
for  1,000  pounds  of  milk.  During  the  ripening,  one 
lot  was  kept  at  32°  F.,  one  at  55°  F.,  one  at  60°  F. 
and  one  at  70°  F.  On  page  345  we  give  the  aver- 


344     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

ages  of  the  4  lots  of  cheese  kept  at  the  different  tem- 
peratures. Whether  we  consider  each  lot  of  cheeses 
by  itself  or  their  averages,  the  results  are  strikingly 
concordant  in  respect  to  the  effect  of  salt  upon  the 
formation  of  proteins  and  their  derivatives  in  the 
ripening  process. 

We  are  to  regard  the  salt  in  cheese  as  being  in 
solution  in  the  whey  held  by  the  cheese,  practically 
forming  a  dilute  brine.  In  common  practice, 
cheese-makers  add  from  2  to  2j/£  pounds  of  salt  to 
the  curd  made 'from  1,000  pounds  of  milk.  Cheese 
thus  salted  contains  about  I  per  cent  of  salt.  Such 
cheese  usually  contains  about  35  to  37  per  cent  of 
water.  Consequently,  under  such  conditions  we 
should  have,  approximately,  a  3  per  cent  brine.  It 
is  evident  that,  in  proportion  as  a  cheese  loses  mois- 
ture by  evaporation,  the  brine  remaining  becomes 
more  concentrated  with  the  advancing  age  of  the 
cheese. 

A  study  of  the  table  leads  to  the  following  state- 
ments : 

(i)  The  amount  of  salt  retained  in  cheese  is  not 
proportional  to  the  amount  of  salt  added  to  the  curd. 
While  salt  was  added  to  the  different  cheeses  in  the 
ratio  of  i:  1.67:  3.33,  the  salt  retained  in  the  cheese 
was  in  the  ratio  of  1:1.40:2.20.  Of  necessity, 
a  considerable  proportion  of  the  salt  added  to  the 
cheese-curd  passes  into  the  whey.  Moreover,  it 
has  been  found  by  examining  different  portions  of 
the  same  cheese  that  the  salt  is  not  commonly 
distributed  with  perfect  uniformity  through  the  cheese 
mass. 


SHOWING  EFFECT   OF  SALT   ON    CHEESE-RIPENING 


Am't 
of  salt 
used 
for 
1000 
Ibs. 
of  milk 

Form  of 
proteins 
and  de- 
rivatives.etc  . 

Nitrogen  expressed  as  percentage  of  nitrogen  in  cheese 

1* 

mos. 

3 
mos. 

6 
mos. 

9 
mos. 

12 
mos. 

18 
mos. 

Lbs. 

Total  water 

Per  cent 

Per  cent 

Per  cent 

Percent  Percent 

Per  cent 

0 

soluble    .... 

23.42 

34.26 

40.52 

49.10  .      51.38 

53.96 

1* 

21.80 

32.10 

37.67 

44.13   !      45.88 

50.73 

2i 

«< 

21.67 

29.92 

34.73 

42.93 

43.52 

44.65 

5* 

"      .... 

18.84 

27.70 

31.70 

37.64 

38.19 

39.62 

0 

Brine-solu- 

ble^ 

17.33 

27.06 

23.27 

21.82 

16.75 

12.56 

1* 

20.86 

28.43 

26.16 

22.38 

17.98 

12.61 

24 

«• 

21.81 

24.47 

28.30 

23.54 

18.04 

13.  It. 

5 

20.73 

29.02 

32.49 

28.81 

23.41 

11.  7i 

0 

Paranuclein 

1.85 

4.44 

3.80 

4.66 

3.83 

3.44 

14 

2.13 

4.47 

3.52 

4.01 

3.72 

3.89 

24 

M 

2.27 

4.55 

3.51 

3.80 

3.30 

3.34 

5 

" 

1.98 

4.35 

3.42 

3.63 

3.23 

2.96 

0 

Caseoses  .  .  . 

3.41 

4.94 

4.94 

5.60 

4.95 

3.87 

li 

3.24 

5.02 

5.17 

4.53 

3.69 

4.04 

24 

«« 

3.21 

4.14 

4.98 

4.16 

3.97 

3.84 

5 

"     ... 

2.75 

4.14 

4.58 

4.08 

4.05 

3.77 

0 

Peptones   .  . 

4.86 

5.02 

4.84 

3.47 

4.13 

2.69 

14 

3.50 

5.16 

4.29 

3.54 

4.87 

3.40 

2i 

•• 

4.20 

4.02 

4.02 

3.97 

3.98 

2.07 

5 

•  4 

2.91 

4.42 

3.74 

3.25 

2.81 

2.14 

0 

Amino  acids 

10.22 

15.86 

22.18 

28.89 

32.19 

35.09 

it 

« 

10.46 
9.78 

14.77 
13.83 

20.13 
19.20 

27.31 
26.72 

29.33 
27.61 

32.36 
29.57 

5 

" 

8.82 

12.97 

17.34 

23.21 

24.40 

24.81 

0 

Ammonia  .  . 

1.67 

2.96 

4.64 

6.54 

7.77 

8.89 

i*    ; 

1.67 

2.53 

3.69 

4.69 

5.36 

7.04 

al 

«« 

1.51 

2.36 

3.13 

4.30 

4.54 

5.83 

5 

" 

1.41 

2.03 

2.64 

3.43 

3.61 

4.70 

0 

Per  cent 

water  in 

cheese  .... 

39.27 

38.22 

35.60 

35.22 

34.C9 

30.96 

14 

36.66 

35.60 

33.50 

32.62 

31.61 

28.  8C 

24 

«« 

35.69 

34.43 

32.31 

31.54 

30.99 

27.68 

5 

" 

33.63 

32.62 

29.52 

29.88 

28.61 

26.97 

0 

Per  cent  salt 

in  cheese.  . 

0 

0 

0 

0 

0 

0 

I'l 

0.59 

0.70 

0.84 

0.94 

0.92 

24 

«« 

0.82 

1.20 

1.15 

1.26 

1.27 

.... 

5 

" 

1.29 

1.50 

1.62 

1.87 

1.83 

1 

345 


346     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

(2)  An  increase  of  salt  in  cheese-curd  results  in 
decreasing   the   amount   of    moisture   held   in   cheese. 
This  fact  is  Very  strikingly  shown  by  the  figures  in 
the  table.       The   cheese   containing  no   salt  retained 
most  moisture,  and   increasing  additions   of   salt  de- 
creased the  amount  of  moisture  held   in  the  cheese. 
The  same  general  relation  held  true  throughout  the 
whole  period  of  investigation. 

(3)  An    increase    of   salt   in    cheese   was    accom- 
panied by  a  decrease  in  the  amount  of  water-soluble 
protein-derived      compounds     and      this      was      true 
through   the   whole    18   months   of   the   investigation. 
While  this  influence  of  salt  is  more  noticeable  in  the 
case  of  the  amino  acids  and  ammonia,   it  is  -clearly 
evident  in  the  case  of  the  paranuclein,  caseoses,  and 
peptones. 

(4)  It  is  readily  seen  from  the  results  embodied 
in  the  table  that  the  rapidity  of  formation  of  water- 
soluble    protein-derived    compounds    is    decreased    in 
the  presence  of  increased  amounts  of  salt  in  cheese. 
This  is  due,  in  part,  to  the  effect  of  salt  in  decreas- 
ing the  amount  of  moisture   held   in   cheese   and,  in 
part,  to  the  direct  retarding  action  of  salt  upon  some 
of  the  agents   that  produce  the  changes   of  cheese- 
ripening. 

Amount  of  rennet-enzym  and  cheese-ripening. — 
Before  any  careful  studies  were  made  of  the  effect 
of  rennet-enzym  upon  the  chemical  changes  of 
cheese-ripening,  there  was  difference  of  opinion 
among  cheese-makers  as  to  whether  the  amount 
of  rennet-extract  used  had  any  influence  on  the 
ripening  of  the  cheese.  The  various  studies  made 
of  the  subject  by  different  investigators  agree  in 


CHEMICAL    CHANGES    IN    RIPENING 


347 


showing     that      rennet-enzym      does     influence     the 
rapidity    of    the    ripening1    process.       In    the    results 

SHOWING    EFFECT    OF   DIFFERENT   AMOUNTS    OF   RENNET 
UPON    CHEESE-RIPENING 


Amount 
of 

Nitrogen  expressed  as  percentage 
of  nitrogen  in  cheese  in  form  of: 

Age 

rennet- 

Condition 

Water 

of 
cheese 

extract 
used  for 
1000 
pounds 

of 
cheese 

in 
cheese 

Water- 
soluble 
proteins 
anH  f\f.- 

Paranu- 
clein.  cas- 
eoses  and 

Amino 
acids 

Ammo- 
nia 

of  milk 

rivatives 

peptones 

Months 

Ounces 

Per  ct. 

Per  ct. 

Per  ct. 

Perct. 

Perct. 

1 

3 

Mormal..  .  . 

37.54 

18.90 

10.31 

8.36 

.... 

1 

6 

Normal..  .  . 

38.06 

23.40 

13.37 

9.47 

.... 

1 

3 

Paraffined  . 

38.45 

18.20 

9.95 

8.29 

1 

6 

Paraffined.. 

38.56 

24.90 

15.30 

9.63 

3 

3 

Normal..  .  . 

35.59 

26.70 

13.34 

12.00 

1.87 

3 

6 

Normal..  .  . 

36.25 

29.70 

15.40 

12.50 

1.86 

3 

3 

Paraffined.. 

37.97 

27.90 

13.39 

12.60 

1.96 

3 

6 

Paraffined.. 

37.61 

33.20 

16.35 

14.70 

2.18 

6 

3 

Normal..  .  . 

33.58 

29.80 

12.02 

16.20 

2.09 

6 

6 

Normal..  .  . 

33.51 

35.40 

15.11 

18.20 

2.60 

6 

3 

Paraffined.. 

37.59 

31.80 

12.84 

17.30 

2.23 

6 

6 

Paraffined.. 

36.79 

36.80 

16.76 

17.30 

2.70 

9 

3 

Normal..  .  . 

31.84 

37.30 

13.47 

21.20 

2.59 

9 

6 

Normal..  .  . 

30.63 

35.50 

13.00 

20.00 

2.50 

9 

3 

Paraffined. 

36.81 

38.90 

14.93 

20.30 

3.73 

9 

6 

Paraffined.. 

35.40 

45.20 

14.36 

26.60 

4.26 

12 

3 

Normal,.  .  . 

28.13 

38.00 

12.05 

22.10 

4.10 

12 

6 

Normal..  .  . 

29.98 

42.40 

14.38 

24.00 

3.60 

12 

3 

Paraffined. 

36.07 

40.40 

14.10 

23.60 

2  93 

12 

6 

Paraffined.. 

34.51 

48.10 

15.34 

27.50 

4.60 

15 

3 

Normal..  .  . 

26.73 

39.10 

12.05 

22.90 

4.53 

IS 

6 

Normal..  .  . 

25.97 

43.60 

13.19 

25.50 

4.31 

IS 

3 

Paraffined.. 

34.35 

41.20 

12.96 

23.80 

4.92 

IS 

6 

Parafined... 

33.21 

49.90 

16.87 

28.00 

5.54 

24 

3 

Normal..  .  . 

24.76 

42.70 

12.30 

25.10 

5.06 

24 

6 

Normal..  .  . 

23.33 

48.50 

14.54     |    28.50 

5.84 

24 

3 

Paraffined.. 

30.93 

46.40 

11.34         28.70         6.52 

24 

6 

Paraffined.. 

28.22 

50.20 

11.75      \    30.80 

7.92 

348     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

given  on  page  347,  the  study  was  made  with  the  use 
of  3  to  6  ounces  of  Hansen's  rennet-extract  in  1,000 
pounds  of  milk.  The  cheeses  were  made  to  con- 
tain about  the  same  amount  of  moisture.  In  each 
case,  one  cheese  was  covered  with  paraffin  in  order 
to  delay  the  evaporation  of  moisture,  while  the  other 
was  kept  in  the  usual  condition. 

The  data  in  the  preceding  table  show  quite  gen- 
erally a  greater  increase  of  water-soluble  protein- 
derived  compounds  in  the  cheese  containing  the 
larger  amount  of  rennet,  other  conditions  being  the 
same.  The  cheeses  covered  with  paraffin  contain 
more  moisture  than  those  not  so  covered  and,  as 
we  should  expect,  show  a  larger  increase  of  soluble 
compounds  than  do  the  other  cheeses;  but  here,  also, 
the  cheese  containing  the  larger  amount  of  rennet 
ripens  more  rapidly  than  the  one  containing  less 
rennet. 

If  we  examine  the  different  classes  of  the  water- 
soluble  protein  and  protein-derived  compounds,  we 
notice  that  the  increase  caused  by  the  increased 
use  of  rennet  is  more  noticeable  in  the  case  of  the 
paranuclein,  caseoses  and  peptones  than  in  the  case 
of  the  amino  acids  and  ammonia,  especially  during 
the  first  6  or  9  months. 

GENERAL  SUMMARY  OF  RESULTS  RELAT- 
ING TO   CONDITIONS   OF   CHEESE- 
RIPENING  AND  CHEMI- 
CAL CHANGES 

Reviewing  briefly  the  results  that  have  been  pre- 
sented in  the  preceding  pages,  we  have  found  that 


CHEMICAL    CHANGES    IN    RIPENING  349 

different   conditions   affect   the    chemical   changes    in 
the  protein  compounds  of  cheese  as  follows: 

(1)  Time. — The  formation  of   water-soluble  pro- 
tein-derived   compounds    increases    as    cheese    ages, 
other  conditions  being  uniform.     The  rate  of  increase 
is,  however,  not  uniform,  since  it  is  much  more  rapid 
in  the  early  than  in  the  succeeding  stages  of  ripen- 
ing. 

(2)  Temperature. — The  amount   of   soluble  pro- 
tein-derived compounds  increases,  on  an  average,  quite 
closely  in  proportion  to  increase  of  temperature,  when 
other  conditions  are  uniform. 

(3)  Moisture. — Other     conditions     being     alike, 
there   is    formed    a    larger   amount    of   water-soluble 
protein-derived     compounds     in     cheese     containing 
more  moisture  than  in  cheese  containing  less  mois- 
ture. 

(4)  Size. — Cheeses    of    large    size    usually    form 
water-soluble   compounds  more   rapidly  than   smaller 
cheeses    under    the    same    conditions,    because    large 
cheeses    lose    their    moisture    less    rapidly    and    after 
the   early   period   of    ripening   have   a   higher   water 
content. 

(5)  Salt. — Cheese    containing    more    salt    forms 
water-soluble    compounds    more    slowly    than    cheese 
containing   less    salt.      This    appears   to   be    due,   in 
part,   to   the   direct   action   of    salt   in   retarding   the 
activity  of  one  or  more  of  the  ripening  agents  and, 
in   part,   to  the  tendency  of  the   salt  to  reduce  the 
moisture  content  of  the  cheese. 

(6)  Rennet. — The   use   of  increased   amounts   of 
rennet-extract     in     cheese-making,     other    conditions 
being     uniform,     results     in     producing     increased 


35O        SCIENCE  AND   PRACTICE    OF    CHEESE-MAKIXG 

quantities  of  water-soluble  protein-derived  compounds 
in  a  given  period  of  time,  especially  such  compounds 
as  paranuclein,  caseoses  and  peptones. 

TRANSIENT  AND  CUMULATIVE  PROD- 
UCTS IN  CHEESE-RIPENING 

In  studying  the  influence  of  various  conditions 
upon  the  chemical  changes  of  the  protein  com- 
pounds in  the  normal  cheese-ripening  process,  we 
have  noticed  that  the  compounds  which  are  grouped 
under  the  names,  paracasein,  caseoses  and  peptones 
usually  vary  within  comparatively  narrow  limits 
and  do  not  appear  to  accumulate  in  the  cheese  in 
constantly  increasing  quantities.  These  compounds 
do  not  appear  to  show  much  definite  regularity 
in  the  amounts  formed  under  different  con- 
ditions. On  the  other  hand,  amino  acids  and  am- 
monia accumulate  in  increasing  amounts  from  the 
early  age  of  the  cheese  during  the  whole  process 
of  normal  ripening.  The  difference  in  the  appar- 
ent behavior  of  these  different  classes  of  com- 
pounds is  most  readily  explained  by  regarding  the 
compounds  first  formed  in  cheese-ripening  as  inter- 
mediate or  transient  products.  Thus,  we  find  para- 
nuclein, caseoses  and  peptones  present  in  the  earliest 
stage  of  cheese-ripening,  and  they  show  a  tendency 
to  increase  somewhat  for  a  period  of  time  and  then 
decrease.  Whatever  may  be  the  precise  chemical 
relation  and  order  of  formation,  the  point  we  wish 
to  keep  in  mind  is  that  the  amounts  of  these  com- 
pounds do  not  increase  regularly  or  accumulate 
continuously  in  the  cheese.  The  extent  to  which 
any  accumulation  occurs  in  these  transient  stages 


CHEMICAL    CHANGES    IN    RIPENING 


351 


depends  upon  the  conditions  of  ripening.  For  ex- 
ample, at  low  temperatures,  the  transient  protein 
products  formed  appear  to  pass  into  other  forms  less 
rapidly  than  at  higher  temperatures,  and  they  tend  to 
accumulate  to  some  extent.  This  can  be  shown  by 
comparing  the  results  secured  with  cheeses  ripened  at 
32°  F.  and  at  70°  F. 


Age 

Percentage   of  ni- 
trogen in  form  of 

Percentage  of  ni- 
trogen in  form  of 

Percentage  of  ni- 
trogen in  form  of 

of 
cheese 

paranuclein  in 
cheese  at 

caseoses  in 
cheese  at 

peptones  in 
•          cheese  at 

32°F. 

70°F. 

32°F. 

70°F. 

32°F. 

70°F. 

Months 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

li 

1.27 

2.03 

1.05 

4.0/ 

1.30 

6.81 

3 

4.05 

3.71 

2.97 

4.63 

2.23 

5.45 

6 

3.44 

2.68 

5.24 

3.37 

4.53 

3.67 

9 

4.47 

3.13 

4.29 

4.24 

4.36 

3.33 

12 

4.15 

2.45 

4.17 

4.12 

4.53 

3.51 

18 

4.12 

2.60V 

5.06 

3.20 

4.17 

1.50 

Now,  quite  different  from  the  behavior  of  these 
compounds  is  that  of  amino  acids,  .which  appear  be- 
yond question  to  be  formed  from  the  peptones,  and 
of  ammonia,  which  is  formed  from  the  decomposition 
of  amino  acids.  Ammonia  is  an  end-product  and  the 
amino  acids  are  end-products  to  a  considerable  extent 
in  cheese  normally  ripened.  They  therefore  accum- 
ulate in  increasing  quantities  under  all  conditions 
that  favor  their  formation. 

INFLUENCE  OF  PRODUCTS  OF  CHEMICAL 

CHANGE  IN  THE  CHEESE-RIPENING 

PROCESS 

Attention  has  been  called  to  the  fact  that  chemi- 
cal changes  in  the  proteins  of  cheese  take  place 


352        SCIENCE   AND   PRACTICE    OF    CHEESE-MAKING 


much  more  rapidly  in  the  early  stages  of  ripening 
than  later.  It  is  shown  that,  in  the  first  3  months 
of  the  1 8-month  period  of  study,  over  65  per  cent 
of  the  nitrogen  was  changed  into  the  form  of 
water-soluble  compounds.  How  can  we  explain 
this  observed  fact  that  the  rate  of  chemical  change,  as 
measured  by  the  formation  of  water-soluble  ni- 
trogen compounds,  decreases  as  the  age  of  cheese 
increases?  The  most  obvious  explanation  is  asso- 
ciated with  the  generally  observed  fact  that  in  fer- 
mentation changes  the  products  of  the  process 
weaken  the  action  of  the  ferment,  often  inhibiting 
it  altogether  (p.  286).  In  cheese,  we  have  an  ac- 
cumulation of  fermentation  products  in  the  form  of 
water-soluble  protein  and  protein-derived  compounds 
and,  apparently,  they  serve  to  diminish  the  action  of 
the  agents  that  cause  the  changes. 

In  this  connection,  it  is  interesting  to  notice  that 
the  end-products,  the  amino  acids  and  ammonia, 
appear  to  exert  a  stronger  influence  than  do  the  other 
soluble  protein  compounds  in  decreasing  the  action  of 
the  ripening  agents.  This  is  indicated  by  the  fol- 
lowing data: 


Age 
of 
cheese 

Percentage  of 
nitrogen  in  form  of 
paranuclein,  caseo- 
ses  and  peptones 

Percentage  of 
nitrogen  in  form  of 
amino  acids  and 
ammonia 

Monthly  average 
rate  of  increase  of 
soluble  nitrogen 
compounds  for  100 
pounds  of  nitrogen 

in  cheese 

Months 

Pounds 

H 

9.05 

11.44 

15.0 

3 

13.66 

16.81 

6.3 

6 

12.71 

23.48 

2.1 

9 

12.17 

31.27 

2.4 

12 

11.63 

33.79 

0.4 

18 

37.00 

0.4 

CHEMICAL    CHANGES    IN    RIPENING  353 

Thus,  it  is  seen  that  the  first-formed  products  of 
cheese-ripening,  paranuclein,  caseoses  and  peptones, 
remain  fairly  uniform,  while  the  amino  acids  and  am- 
monia continuously  increase. 

WHY  MOISTURE  INFLUENCES  THE 
CHEESE-RIPENING  PROCESS 

We  have  seen  that  an  increased  moisture  content 
in  cheese  favors  more  active  chemical  changes  in 
the  process  of  ripening.  This  may  be  due  to  one  or 
both  of  two  effects.  First,  moisture  in  itself  may 
favor  the  activity  of  the  ripening  ferments.  It  is  well 
known  that  moisture  is  necessary  for  the  action  of 
ferments  and  that  increase  of  moisture  above  a  certain 
amount  increases  their  action.  Second,  the  presence 
of  increased  amounts  of  moisture  serves  to  dilute  the 
fermentation  products  and,  to  that  extent,  to  counter- 
act their  unfavorable  effect. 

In  ordinary  cheese-ripening,  there  is  a  constant 
loss  of  moisture  and  this  serves  to  make  more  con- 
centrated the  fermentation  products,  which  are 
increasing  at  the  same  time  the  moisture  is  de- 
creasing. Accordingly,  after  3  to  6  months,  differ- 
ence in  moisture  appears  to  exert  a  more  marked 
influence  upon  the  increased  formation  of  soluble 
nitrogen  compounds  than  in  the  early  stages  of 
ripening. 


CHAPTER  XXV 

Causes  of  Chemical  Changes  hi  Cheese- 
Ripening 

A  large  amount  of  work  has  been  done  during-  the 
past  30  years  in  connection  with  different  varieties 
of  cheese,  in  an  effort  to  ascertain  what  agents  cause 
the  changes  taking  place  in  cheese  during  the  ripen- 
ing process.  Many  of  the  results  have  been  peculiarly 
confusing  and  progress  has  been  slow.  Much  of  this 
work  has  been  done  with  the  hard  types  of  cheese, 
the  Emmenthaler  in  Europe  and  the  cheddar  in  Eng- 
land and  America.  The  scope  of  this  book  does  not 
permit  an  historical  review  of  these  investigations, 
and  the  most  we  can  hope  to  do,  within  the  assigned 
limits  of  treatment,  is  to  give  a  brief  summary  of 
what  may  be  regarded  as  the  present  state  of  knowl- 
edge in  respect  to  the  causes  of  cheese-ripening  in 
the  case  of  cheddar  cheese.  It  is  well  to  preface  our 
discussion  with  the  statement  that  the  amount  we 
actually  know  at  present  is  disappointingly  small,  and 
how  much  of  what  we  think  we  know  now  will  be 
modified  by  further  investigation  no  one  can  con- 
fidently say.  In  our  treatment  of  the  causes  of  cheese- 
ripening,  we  confine  our  attention  mainly  to  the 
changes  that  take  place  in  the  protein  compounds, 
which  come  originally,  as  we  know,  from  milk-casein ; 
because,  in  this  portion  of  the  cheese  substance,  the 
most  profound  and  extensive  changes  occur,  changes 

354 


CAUSES    OF    RIPENING    CHANGES  355 

which  are  most  intimately  connected  with  the  chang- 
ing qualities  that  appear  in  the  process.  As  pre- 
viously stated,  the  cheese-ripening  process,  considered 
from  a  chemical  standpoint,  consists  mainly  in  the 
change  of  the  complex  protein,  paracasein,  as  it  exists 
in  cheese-curd,  into  a  number  of  less  complex  com- 
pounds. 

Many  difficulties  beset  the  experimental  study  of 
cheese-ripening,  some  of  which  will  be  briefly  noticed 
later.  One  of  the  great  difficulties  in  the  past  has 
been  a  failure  to  recognize  that  there  was  more  than 
one  agent  at  work  in  the  process  of  cheese-ripening. 
The  investigator  is  always  at  a  disadvantage  when 
his  point  of  view  is  too  narrow,  since  he  inevitably 
overlooks  essential  details,  and  interprets  his  results 
within  the  narrow  range  of  his  vision.  This  truth  has 
been  amply  illustrated  in  the  history  of  the  investiga- 
tion of  the  causes  of  -cheese-ripening,  since  many  in- 
vestigations were  based  upon  the  conception  that  only 
one  agent  was  the  cause;  and  the  object  of  the  inves- 
tigator was,  unconsciously,  not  so  much  to  find  out 
what  the  real  cause  might  be  as  to  show  that  the  one 
particular  agency  he  had  in  mind  was  the  actual  and 
sole  cause. 

We  shall  not  attempt  to  treat  the  subject  in  the 
order  of  its  historical  development,  but  rather  in  the 
order  in  which  the  different  agencies  become  most 
active  in  the  ripening  process.  So  far  as  our  present 
knowledge  goes,  the  different  agents  taking  part  in 
the  change  of  the  protein,  paracasein,  into  simpler 
proteins  and  protein-derived  compounds  are  the  fol- 
lowing : 

I.     Some  acid,  usually  lactic. 


356       SCIENCE  AND   PRACTICE   OF    CHEESE-MAKING 

2.  Rennet-enzym. 

3.  Galactase. 

4.  Micro-organisms,  commonly  bacteria. 

Just  what  part  is  played  by  each  agent  in  the  forma- 
tion of  water-soluble  proteins  and  derived  proteins, 
or  what  interdependence  there  may  be  of  the  work 
of  one  agent  upon  the  products  of  the  work  of 
another,  we  are  at  present  able  to  say  only  in  part, 
and  not  very  definitely  at  that.  We  will  now  present 
an  outline  of  what  we  may  conceive  as  the  distribu- 
tion of  work  among  these  different  agents  in  the  light 
of  the  experimental  results  that  are  now  available. 
We  are  conscious  of  the  possibility,  or  rather  prob- 
ability, that  some  of  these  statements  will  need 
revision  in  the  near  future. 

ACTION  OF  ACIDS  IN  CHEESE-RIPENING 

The  necessity  of  the  presence  of  some  acid  in  milk 
and  in  cheese-curd  during  the  process  of  making 
cheddar  cheese  seems  to  have  been  well  established, 
since  cheese  made  without  acid  fails  to  ripen  satis- 
factorily. In  the  absence  of  acid,  little  or  no  brine- 
soluble  protein  or  water-soluble  substance  is  formed, 
even  after  long  periods  of  time.  The  work  of  acid, 
whatever  may  be  the  way  in  which  its  specific  influ- 
ence is  exerted  in  cheese-ripening,  is  something  like 
this:  Lactic  acid  is  formed  by  the  action  of  micro- 
organisms upon  milk-sugar  during  the  process  of 
cheese-making;  and  its  formation  continues  not  only 
during  the  time  the  curd  is  in  the  cheese- vat  but 
also  in  the  curd  as  it  is  put  in  the  press  and  later. 
Under  normal  conditions,  the  acid  continues  to  be 
formed  so  long  as  any  milk-sugar  remains  in  the 


CAUSES    OF    RIPENING    CHANGES 


357 


cheese.  Just  how  long  that  is,  varies  according  to 
conditions  of  manufacture  and  especially  with  the 
temperature  at  which  the  cheese  is  kept  during  the" 
ripening.  Under  ordinary  conditions,  all  sugar  in 
cheese  disappears  within  two  weeks.  Roughly 
speaking,  there  is  between  I  and  2  per  cent  of  milk- 
sugar  in  cheese  when  put  in  the  press.  How  rapidly 
this  undergoes  change  can  be  seen  from  the  following 
illustrations,  in  which  three  different  cheeses  are 
represented : 


MILK-SUGAR    IN    CHEESE 


No.  1 

No.  2 

No.  3 

When  put  in  press 

Per  cent 
1  70 

Per  cent 
0  77 

Per  cent 
1  52 

3  hours  after  being  in  press  

1.05 

0  68 

0  64 

6  hours  after  being  in  press         .    ... 

0  68 

0  44 

12  hours  after  being  in  press  

0.68 

0  80 

15  hours  after  being  in  press  

0.58 

2  days  after  being  in  press                  .  .  . 

0  58 

0  10 

0  36 

0  50 

0  04 

0  32 

1  week  after  being  in  press  
2  weeks  after  being  in  press  

0.10 
0.07 

0.03 
0.00 

0.22 
trace 

These  figures  illustrate  well  the  great  variation  in 
detail  that  may  occur  in  the  disappearance  of  milk- 
sugar  in  cheese,  which  means,  of  course,  the  forma- 
tion of  lactic  acid. 

At  no  stage  of  the  process  of  making  cheddar 
cheese,  and  in  no  cheese,  do  we  find,  under  normal 
conditions,  uncombined  lactic  acid  as  such,  or  what 
we  call  free  lactic  acid.  What  then  becomes  of  the 
lactic  acid  known  to  be  formed?  There  exist  in  the 
milk  substances  which  are  ready  to  combine  with 
lactic  acid  as  fast  as  it  is  formed  and  to  change  the 
acid  from  the  active  condition  of  a  free  acid  to  that 


358        SCIENCE   AND   PRACTICE   OF    CHEESE-MAKING 

of  a  neutral  salt.  These  substances  are  chiefly  lime 
compounds  or  compounds  containing  calcium  as  a 
base.  Over  one-half  and,  probably,  about  three- 
fourths,  of  the  calcium  compounds  in  milk  are  in  such 
form  as  enable  them  to  combine  with  lactic  acid.  A 
considerable  part  of  the  calcium  in  milk  is  in  com- 
bination with  phosphoric  acid  in  the  form  of  insoluble 
compounds,  probably  dicalcium  phosphate  in  large 
part,  which  is  held  in  suspension  in  the  form  of  very 
minute,  solid  particles.  Some  believe  that  the  cal- 
cium phosphate  is  in  direct  combination  with  casein 
in  milk.  The  action  that  probably  takes  place  can  be 
represented  as  follows: 

Lactic  acid  -j-  insoluble  calcium  phosphate  =  cal- 
cium lactate  +  soluble  calcium  phosphate  (mono  or 
acid-calcium  phosphate).  Now,  mono-calcium  phos- 
phate is  an  acid  salt ;  it  neutralizes  alkalis  and  tastes 
sour.  Therefore,  when  we  talk  about  lactic  acid  in 
cheese-making,  we  really  mean  the  products  formed 
by  the  action  of  lactic  acid — calcium  lactate  and  cal- 
cium acid  phosphate. 

The  first  effect  of  the  formation  of  these  soluble 
lime  salts  is  to  promote  the  coagulating  effect  of 
rennet;  and  the  particular  thing  accomplished  by 
ripening  milk  for  cheese-making  is  the  formation  in 
small,  but  sufficient,  quantities  of  calcium  lactate  and 
soluble  calcium  phosphate.  The  succeeding  changes 
in  curd,  the  formation  of  a  superficial  film  on  each 
small  piece  of  curd,  the  shrinking  with  the  simul- 
taneous expulsion  of  whey,  the  stringing  on  a  hot 
iron,  the  change  in  texture  of  curd  to  the  softer, 
velvety  form,  resembling  the  meat  of  a  chicken's 
breast,  the  plastic  condition — these  changes  all 


CAUSES    OF    RIPENING    CHANGES 


359 


appear  to  be  associated  with  the  continued  forma- 
tion of  lactic  acid,  resulting  in  larger  amounts  of 
calcium  lactate  and  acid  phosphate.  To  what  ex- 
tent temperature  and  action  of  rennet-enzym  share 
in  producing  these  changes  cannot  be  definitely 
stated  now.  It  has  been  pretty  satisfactorily  estab- 
lished that  in  cheddar  cheese-making  there  is,  con- 
trary to  what  was  believed  at  one  time,  no 
combination  of  any  kind  between  the  lactic  acid  and 
the  protein  of  the  cheese-curd,  but  that  the  acid 
formed  is  practically  all  used  by  the  lime  salts  of 
the  curd  in  the  formation  of  the  calcium  compounds 
mentioned. 

During  the  cheese-making  process,  the  cheese-curd 
or  paracasein  undergoes  some  very  marked  changes, 
as  we  have  just  noticed  above.  We  have  a  simple 
means  of  measuring  the  extent  of  these  changes, 
depending  on  the  behavior  of  the  curd  when  treated 
with  warm  (123°  to  132°  F.),  dilute  brine  (a  5  per 
cent  solution  of  common  salt  in  water)  (p.  330). 
The  changes  taking  place  and  thus  measured  can  be 
illustrated  as  follows,  using  the  results  of  a  special 
experiment,  taken  from  the  records  of  the  New  York 
experiment  station: 


Per  cent  of  pro- 
tein soluble  in 
brine  solution 

Per  cent  of  pro- 
tein soluble  in 
water 

When  curd  was  cut     

3.13 

When  whey  was  removed 

4  50 

30  IS 

3  77 

2    hours  after  curd  was  put  in  press 
9£  hours  after  curd  was  put  in  press 

46.46 
96.06 

4.25 
6.48 

It   is   seen    that   the   increase   of   the   brine-soluble 
protein  is  very  rapid  between  the  time  when  the  whey 


360        SCIENCE   AND    PRACTICE    OF    CHEESE-MAKING 

was  removed  and  the  curd  was  put  in  press.  The 
peculiar  behavior  of  the  curd  during  the  cheddaring 
process  is  probably  due  to  the  formation  of  the 
brine-soluble  substance;  and  the  formation  of  this 
substance  appears  to  be  associated,  at  least  in  consider- 
able measure,  with  the  formation  of  soluble  lime  salts 
resulting  from  the  action  of  lactic  acid.  From  some 
work  done  at  the  New  York  experiment  station,  it 
seems  that  when  this  brine-soluble  compound  is  not 
formed,  we  do  not  get  water-soluble  substances, 
and  this  means  that  we  get  no  cheese-ripening.  In 
other  words,  the  formation  of  the  brine-soluble  sub- 
stance appears  to  be  prerequisite  to  further  ripening 
changes. 

Reviewing  briefly  the  action  of  acid  in  cheese-mak- 
ing and  cheese-ripening,  its  chief  work  appears  to  be 
combination  with  the  insoluble  lime  salts  of  the 
milk,  producing  calcium  lactate  and  calcium  acid 
phosphate.  These  compounds,  in  conjunction  with 
the  degree  of  heat  used  and,  perhaps,  also  in  asso- 
ciation with  the  action  of  rennet-enzym,  produce 
marked  changes  in  the  curd  in  respect  to  body, 
texture  and  solubility  in  brine  solution.  In  the 
cheese-making  process,  the  insoluble  portion  of 
the  curd  begins  to  change  into  a  form  that  is  soluble 
in  warm,  5  per  cent  brine,  this  change  taking  place 
rapidly  during  the  cheddaring  operation  and  con- 
tinuing until  all  the  protein  of  the  curd  is  in  this 
form;  the  change  appears  to  be  complete  9  or  IO 
hours  after  the  curd  is  put  in  press.  Then  this 
brine-soluble  curd  begins  to  change  into  an  in- 
soluble form,  this  reverse  change  going  on  very 
rapidly  for  a  few  hours  and  then  more  gradually  for 
many  months.  From  this  insoluble  form  appear  to 


CAUSES    OF    RIPENING    CHANGES  361 

come  the  water-soluble  proteins  and  protein  deriva- 
tives that  are  found  in  cheese.  Much  work  yet  re- 
mains to  be  done  before  all  the  details  of  the  action 
of  acid  in  cheese-making  are  fully  understood. 

ACTION   OF  RENNET-ENZYM   IN   CHEESE- 
RIPENING 

For  a  long  time,  there  was  doubt  as  to  whether 
rennet-extract  had  anything  to  do  with  cheese-ripen- 
ing. It  may  be  now  regarded  as  definitely  settled 
that  rennet-extract  contains  a  peptic  ferment  which 
has  a  curd-dissolving  power.  This  fact  has  nothing 
necessarily  to  do  with  the  question  as  to  whether  the 
peptic  enzym  is  the  same  as  the  coagulating  enzym, 
or  whether  two  different  enzyms,  each  with  a  dif- 
ferent function,  are  present.  The  action  of  rennet 
in  cheese-ripening  is  quite  similar  to  that  of  a  pepsin 
digestion.  There  is  one  important  condition  for  the 
peptic  action  of  the  rennet-enzym — the  presence  of 
an  amount  of  acid  or  acid  salts,  corresponding  to 
about  0.3  per  cent  of  lactic  acid.  The  acid  produced 
in  cheese-curd  and  cheese  furnishes  the  needed  con- 
ditions. Whether  this  is  the  chief  function  of  acid 
in  connection  with  the  formation  of  water-soluble 
proteins  and  derived  proteins  in  cheese-ripening,  or 
whether  the  salts  formed  by  lactic  acid  exercise  some 
influence  apart  from  rennet  action,  may  not  be  re- 
garded as  satisfactorily  determined  at  the  present  time. 

In  order  to  study  the  effect  of  rennet-enzym  in  dis- 
solving the  insoluble  protein  of  cheese-curd,  it  is 
necessary  to  destroy  the  enzyms  and  micro-organisms 
present  in  milk.  This  is  done  by  heating  the  milk 
to  a  temperature  of  185°  to  208°  F.,  after  which  the 


362        SCIENCE   AND    PRACTICE    OF    CHEESE-MAKING 

milk  is  cooled  and,  in  order  to  prevent  bacterial  action, 
treated  with  chloroform  before  being  made  into 
cheese.  The  heating  of  the  milk  to  the  stated  tem- 
perature diminishes  the  readiness  and  completeness 
with  which  the  rennet-extract  coagulates  milk-casein; 
but  the  power  af  prompt  coagulation  by  rennet  can 
be  restored  by  addition  of  calcium  chlorid  or  carbon 
dioxid  gas  or  any  ordinary  acid  or  acid  salt.  In  thus 
eliminating  other  factors  otf  cheese-ripening  than  ren- 
net-enzym,  we  necessarily  produce  conditions  that 
do  not  exist  in  normal  cheese-making,  such  as  (i) 
heated  milk,  (2)  absence  of  milk-enzyms,  (3)  absence 
of  enzym-forming  or  acid-producing  micro-organisms, 
and  (4)  the  addition  of  calcium  chlorid  or  carbon 
dioxid  or  lactic  acid.  Several  experiments  were  car- 
ried on  at  the  New  York  experiment  station  under 
the  foregoing  conditions  and,  in  the  table  following, 
we  give  some  of  the  results  of  this  work.  Lactic  acid, 
when  used,  was  added  to  form  0.2  per  cent  of  the  milk. 


PEPTIC     ACTION     OF     RENNET     IN     CHEESE     WITH     AND 
WITHOUT    ACID 


Percentage  of  nitrogen  in  form  of: 

Acrp  of 

Cheese 

made 

when 
analyzed 

with  or 
without 
acid 

Water-soluble 
proteins  and 
derived 
compounds 

Brine- 
soluble 
proteins 

Paranuclein, 
caseoses  and 
peptones 

Amino 
acids 

Fresh 

Without 

6.07 

3.75 

5.46 

0.81 

Fresh 

With 

4.55 

26.80                    3.78 

0.77 

12  months 

Without 

8.47 

3.36 

4.51 

3.96 

1  2  months 

With 

25.10 

11.59 

20.87 

4.98 

In  studying  this  table,  we  can  readily  observe  the 
following  indications : 


CAU8KS    OF    RIPENING    CHANGES  363 

(1)  When  no  acid,  or  acid  salt,  is  present  in  the 
cheese-making   process,    practically    no   changes    take 
place  in  the  protein  of  the  green  cheese,  even  in  the 
course  of  a  year;    the  different  classes  of  compounds 
remain  about  the  same  in  amount  at  the  end  of  a  year 
as   in   the    fresh   cheese.     Rennet-enzym,    in   the   ab- 
sence of  acid  or  acid  salts,  has  practically  no  dissolv- 
ing effect  on  the  protein  of  green  cheese  and,  there- 
fore, does  little  or  no  work  in  the  formation  of  water- 
soluble  protein  in  the  process  of  cheese-ripening. 

(2)  When  lactic  acid  was  added  to  milk  at  the 
rate  of  0.2  per  cent,  the  results  were  in  marked  con- 
trast with  those  given  when  no  acid  was  used.     Thus, 
we  have   (a)   a  considerable  amount  of  brine-soluble 
protein  in  the  fresh  cheese,  and  (b)   a  large  increase 
of  water-soluble  nitrogen   compounds  at  the   end  of 
12  months.     It  is  noticeable  that  the  increase  in  these 
water-soluble   compounds    is   largely   confined   to   the 
paranuclein,   caseoses  and   peptones;    the   amount  of 
amino  acids  remains  small  as  compared  with  a  normal 
cheese  of  the  same  age. 

That  rennet-enzym  acts  like  pepsin  in  dissolving  the 
protein  of  fresh  cheese-curd  has  been  shown  by 
experimental  work.  Heated  milk  (100  cubic  centi- 
meters), treated  with  chloroform  to  prevent  bacterial 
action,  was  put  into  sterilized  bottles ;  0.22  cubic  cen- 
timeter of  Hansen's  fresh  rennet-extract  was  added 
to  some  bottles,  and  to  others  0.06  gram  of  aseptic 
scale-pepsin  for  each  7  grams  of  protein  in  milk.  In 
the  case  of  one-half  of  the  bottles,  0.5  cubic  centimeter 
of  pure  lactic  acid  was  added.  The  bottles  were  kept 
at  60°  F.  The  germ  content  was  shown  to  be  insig- 
nificant. In  one  set  of  experiments  milk  was  used 


364       SCIENCE  AND  PRACTICE   OF   CHEESE-MAKING 

and  in  another,  cheese.  The  results  obtained  with 
rennet-extract  and  commercial  pepsin  in  the  case  of 
milk  are  given  below.  • 


COMPARISON  OF  DIGESTING  ACTION  OF  RENNET-EXTRACT 
AND   COMMERCIAL    PEPSIN 


Percentage  of  total  nitrogen  in  form  of  : 

Kind  of 

With  or 

Age  of 

enzym 
material 
used 

without 
lactic  acid 

milk 
when 
analyzed 

Water-soluble 
proteins  and 
derivatives 

Caseoses 
and 
peptones 

Amino 
acids 

Months 

Fresh 

9.98 

Rennet  .  . 

Without 

1 

1L96 

s'.so 

'6.47 

Pepsin.  .  . 

Without 

1 

8.91 

2.22 

6.69 

Rennet.  .  . 

With 

1 

27.52 

20.39 

7.13 

Pepsin.  .  . 

With 

1 

33.51 

25.93 

7.58 

Rennet..  . 

Without 

3 

16.44 

8.06 

8.37 

Pepsin  .  .  . 

Without 

3 

11.42 

2.42 

9.00 

Rennet.  .  . 

With 

3 

39.17 

29.01 

10.16 

Pepsin  .  .  . 

With 

3 

44.47 

34.22 

10.25 

Rennet.  .  . 

Without 

6 

15.95 

12.74 

3.21 

Pepsin  .  .  . 

Without 

6 

10.34 

6.60 

3.74 

Rennet.  .  . 

With 

6 

44.00 

38.46 

5.54 

Pepsin  .  .  . 

With 

6 

48.76 

44.74 

4.02 

Rennet.  .  . 

Without 

9 

18.00 

12.90 

5.13 

Pepsin.  .  . 

Without 

9 

10.08 

6.51 

3.57 

Rennet.  .  . 

With 

9 

50.77 

42.66 

8.11 

Pepsin  .  .  . 

With 

9 

56.96 

48.05 

8.91 

An  examination  of  this  table  shows  that  there  is  a 
very  fair  parallel  in  the  digesting  action  of  rennet- 
extract  and  commercial  pepsin.  Thus,  the  action  in- 
creases when  acid  is  added;  the  increase  of  soluble 
proteins  is  largely  confined  to  caseoses  and  peptones; 
the  amount  of  amino  acids  remains  practically 
unchanged;  no  ammonia  is  formed.  The  results 


CAUSES    OF    RIPENING    CHANGES 


365 


indicate  that  the  action  of  pepsin  was  able  to 
account  for  all  the  changes  observed  in  the  case  of 
rennet-extract  in  the  presence  of  acid.  But  an  inter- 
esting difference  is  observable  in  connection  with  the 
results  when  no  acid  was  present.  We  notice  that, 
in  the  absence  of  acid,  there  is  a  gradual  increase  of 
soluble  compounds  in  the  case  of  rennet-extract  from 
9.98  to  18.00  at  the  end  of  9  months,  but  no  such 
increase  is  seen  with  the  commercial  pepsin.  This 
difference  suggests  that  the  rennet-extract  contained, 
in  addition  to  the  peptic  ferment  proper,  a  digesting 
enzym  not  contained  in  the  commercial  pepsin;  this 
enzym  shows  the  ability  to  dissolve  insoluble  protein 
even  in  the  absence  of  acid.  This  observation  has 
been  confirmed  by  the  work  of  others. 

The   effect   of  commercial  pepsin   in   increasing   in 
cheese   the   amount   of   water-soluble   proteins,    when 

EFFECT    OF    COMMERCIAL    PEPSIN    IN    CHEESE-RIPENING 


Nitrogen,  expressed  as  percentage  of  nitrogen 

in  cheese,  in  form  of: 

Age  of 

No.  of 

cheese 

Form  of 

experi- 

when 

Enzyms 

Water- 

Para- 

ment 

ana- 
lyzed 

added 

soluble 
proteins 
and  de- 

Brine- 
soluble 

nuclein  , 
caseoses 
and  pep- 

Amino 
acids 

Ammo' 
nia 

rivatives 

tones 

Per  cent 

Per  cent 

Percent 

Perct. 

Perct. 

1 

Fresh 

Rennet- 

extract 

4.76 

65.45 

2.41 

2.36 

.0 

1 

6  months 

28.37 

17.14 

15.87 

6.35 

2.00 

2 

Fresh 

Rennet 

6.97 

36.76 

4.11 

2.86 

.0 

2 

6  months 

andl  gm. 
pepsin 

29.80 

17.04 

16.47 

7.10 

1.91 

3 

Fresh 

Rennet 

25.00 

59.53 

22.80 

2.20 

.0 

&  15  gm. 

3 

3  months 

pepsin 

46.67 

11.61 

41.00 

5.68 

0.49 

366       SCIENCE   AND   PRACTICE   OF    CHEESE-MAKING 


used  in  increasing  amounts,  is  shown  by  the  results 
given  on  page  365,  which  were  obtained  in  an  experi- 
ment in  which  the  cheese  was  made  in  an  entirely 
normal  way,  except  that  hydrochloric  acid  was  used 
in  place  of  lactic  acid  or  a  "starter." 

The  following  tables  are  taken  from  the  records  of 
the  Wisconsin  experiment  station : 

DIGESTING  ACTION   OF  DIFFERENT  AMOUNTS  OF  RENNET- 
EXTRACT    IN    CHEESE 


Amount  of 

Age  of 

Percentage  of  nitrogen  in  form  of: 

rennet- 

cheese 

extract 
used 

when 
analyzed 

Water  soluble 
proteins  and 
derivatives 

Caseoses  and 
peptones 

Amino 
acids 

Ounces 

Months 

3 

1 

13.80 

10.18                       3.62 

12 

1 

18.85 

15.17 

3.68 

24 

1 

24.83 

21.06 

3.77 

3 

3 

23.33 

11.77 

11.56 

12 

3 

31.93 

20.18 

11.75 

24 

3 

34.54 

22.80 

11.74 

DIGESTING    ACTION     OF     RENNET-EXTRACT     AND     PEPSIN 
IN    CHEESE 


Cheese  made 
with  large 
amount  of 
rennet  and 
with  rennet 
plus  pepsin 

Age  of 
cheese 
when 
analyzed 

Percentage  of  nitrogen  in  form  of: 

Water-soluble 
proteins  and 
derivatives 

Caseoses  and 
peptones 

Amino 
acids 

Normal  cheese 
Normal  cheese 
and  pepsin  . 

70  days 
70  days 

26.67 
37.47 

14.57 
25.07 

12.10 
12.40 

We  may  summarize  as  follows  the  results  estab- 
lished by  investigation  regarding  the  relation  of  ren- 
net-extract to  the  cheese-ripening  process: 


CAUSES    OF    RIPENING    CHANGES  367 

(1)  Rennet-extract  contains  an  enzym  which  has 
the   power   of   digesting   or    dissolving   the    insoluble 
protein  in  cheese. 

(2)  Such  digesting  action  by  rennet-extract  does 
not  take  place  in  cheese  which  has  been  made  without 
any  acid  or  acid  salt  in  the  milk  and  curd. 

(3)  The  digestive  action  of  the  enzym  contained 
in  rennet-extract  exerts   its  digesting  power  only  in 
the  presence  of  acids  or  acid  salts.       In  the  case  of 
normal  cheese,  the  acid  formed  in  the  cheese-making 
process  is  lactic  acid,  which,   however,  does  not  act 
as  free  acid,  since  it  reacts  with  calcium  salts,  form- 
ing neutral  calcium  lactate  and  calcium  acid  phosphate 
and,  probably,  citrate.     The  acid  salts  enable  the  ren- 
net-enzym  to  exert  its  digesting  power.       The  same 
general  result  may  be  accomplished  by  adding  a  free 
acid  or  an  acid  salt  to  milk  during  the  cheese-making 
process. 

(4)  The  extent  to  which  the  digesting  enzym  of 
rennet-extract  can  act  depends  largely  upon  the  degree 
of  acidity  developed  in  the  cheese-making  process.     It 
is  probable  that  no  action  begins  until  the  equivalent 
of  0.30  per  cent  of  lactic  acid  has  been  formed. 

(5)  The  products  formed  by  rennet  digestion  of 
cheese   proteins    are    largely   confined   to    the    bodies 
known     as     caseoses     and     peptones,     only     small 
amounts  of  amino  acids  being  formed  and  little  or 
no  ammonia. 

(6)  Increased    use    of    rennet-extract    in    cheese- 
making  results  in  a  more  rapid  formation  of  water- 
soluble  protein  compounds.     This  is  not  due,  as  some 
formerly  thought,  to  an  increased  amount  of  water  in 
cheese,  which  was  supposed  to  be  a  necessary  result 


368       SCIENCE   AND   PRACTICE   OF    CHEESE-MAKING 

of  using  larger  amounts  of  rennet-extract.  Increased 
amounts  of  whey  in  cheese  may,  if  not  too  excessive, 
favor  more  rapid  action  of  the  peptic  ferment  in 
rennet,  because  increase  of  whey  in  cheese  means 
increase  of  milk-sugar  and  this  means  more  lactic 
acid. 

(7)  Commercial  pepsin,  when  used  in  milk  and 
cheese,    behaves     in    a    manner    closely    resembling 
rennet-extract;    since  it  acts  only  in  the  presence  of 
some   a'cid   or    acid    salt   and    forms   relatively   small 
amounts  of  amino  acids  as  compared  with  caseoses 
and  peptoojes. 

(8)  Rennet-extract,  therefore,  contains  an  enzym 
which  has  the  power  of  performing  the  same  kind  and 
amount  of  digesting  work  in  cheese-ripening  as  pepsin. 

(9)  Rennet-extract   appears   to   contain,    in   addi- 
tion  to   the   peptic   ferment,   another   ferment   which 
has  the  power  to  digest  milk-casein  to  some  extent  in 
the  absence  of  acids  or  acid  salts. 

ACTION  OF  GALACTASE  IN  CHEESE- 
RIPENING 

The  main  characteristics  of  the  milk-enzym,  galac- 
tase,  have  been  discussed  already  (p.  297).  It  has 
been  shown  that  galactase  prepared  from  separator- 
slime  in  the  manner  described  by  Babcock  and  Rus- 
sell contains,  at  least,  two  other  enzyms.  But  we  are 
not  particularly  interested  to  know  in  this  discussion 
whether  galactase  is  one  or  two  or  more  enzyms ; 
the  point  of  importance  here  is  that  milk  contains  a 
substance  which  has  the  power  under  certain  condi- 
tions of  converting  milk-casein  and  the  paracasein 
of  cheese-curd  into  soluble  forms  of  proteins  and 


CAUSES    OF    RIPENING    CHANGES  369 

protein  derivatives.  The  fact,  first  discovered  by 
Babcock  and  Russell,  that  there  is  such  an  enzym 
has  been  abundantly  confirmed  by  work  done  at 
the  New  York  experiment  station  and  elsewhere. 
The  work  done  by  the  discoverers  in  studying  the 
properties  of  galactase  led  them  to  regard  as  one 
of  the  distinguishing  characteristics  of  this  enzym 
its  ability  to  convert  casein  and  paracasein  into 
simpler  proteins  and  protein  derivatives,  finally 
forming  ammonia.  On  the  basis  of  this  property, 
the  conclusion  was  reached  by  them  that  galactase 
is  the  chief  agent  in  the  ripening  of  cheddar  cheese. 
Work  done  at  the  New  York  experiment  station 
failed  to  confirm  the  conclusion  that  galactase 
could  form  ammonia  in  the  case  of  either  milk  or 
cheese.  In  carrying  on  the  work  in  New  York, 
cheese  was  made  from  milk  to  which  chloroform  had 
been  added  and  the  cheese  was  kept  in  an  atmosphere 
of  chloroform,  in  order  to  prevent  the  action  of  micro- 
organisms. The  only  ripening  agents  present  were, 
therefore,  galactase  and  the  enzym  or  enzyms  of 
rennet.  Cheese,  thus  made  and  kept,  has  de- 
veloped no  ammonia,  or  possibly  slight  traces  only, 
even  after  24  months.  The  data  on  the  next  page 
illustrate  this  fact. 

Stated  in  a  general  way,  these  results  show  that  ( I ) 
in  cheese  made  and  ripened  in  the  presence  of  chloro- 
form, the  amount  of  caseoses  and  peptones  is  largely  in 
excess  of  the  amount  of  amino  acids;  (2)  the  reverse 
is  true  in  normal  cheese;  (3)  that  ammonia  appears 
in  normal  cheese  much  earlier  and  in  larger  amounts 
than  in  chloroformed  cheese,  appearing  in  the  latter 
only  after  12  months.  About  as  much  ammonia  ap- 
peared in  the  normal  cheese  in  I  month  as  appeared  in 


370 


SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


the  chloroformed  cheese  in  2  years.  The  amount  of 
ammo  acids  formed  in  the  chloroformed  cheese  in  2 
years  was  about  equal  to  the  amount  formed  in  the 
normal  cheese  at  5^2  months. 

From  these   results,   it  is   seen  that,   in   a  normal 
cheese,  the  amino  acids  continuously  increase,  while 

DIFFERENCE   IN   CHARACTER  OF   CHEMICAL   CHANGES   IN 
NORMAL  AND    IN    CHLOROFORMED    CHEESE 


Age 

Percentage  of  nitrogen  in  form  of: 

Character  of 

cheese 

Water-soluble 

Caseoses 

Amino 

Ratio 

proteins  and 
derivatives 

and  pep- 
tones 

acids 

of 
(0  to  (2) 

Ammo- 
nia 

Months 

1      (0 

(2) 

Normal  cheese 

1 

16.70 

2.95 

5.42 

:  1.80 

0.86 

Chloroform  " 

1 

8.73 

3.71 

0.86 

:0.23 

.00 

Normal 

li 

20.30 

2.51 

8.49 

:3.40 

1.29 

Chloroform  ' 

li 

12.00 

7.31 

1.82 

:0.25 

0.00 

Normal 

3i 

29.80 

5.37 

12.60 

:2.40 

2.51 

Chloroform  ' 

3i 

17.50 

10.20 

3.22 

:0.31 

0.00 

Normal 

5^ 

34.60 

4.97 

18.50 

:3.70 

3.38 

Chloroform  ' 

5i 

22.30 

12.40 

4.73 

:0.39 

0.00 

Normal 

7 

36.10 

3.08 

20.10 

:6.50 

4.42 

Chloroform  ' 

7 

24.00 

10.90 

8.11 

:0.74 

0.00 

Normal 

9 

37.85 

2.70 

23.50 

:8.70 

4.87 

Chloroform  ' 

9 

29.50 

12.52 

11.60 

:0.93 

0.00 

Normal 

12 

42.30 

3.03 

24.87 

:8.22 

5.69 

Chloroform  '" 

12 

34.70 

11.89 

15.77 

:  1.33 

0.35 

Normal 

IS 

45.10 

4.47 

27.43 

:6.14 

6.04 

Chloroform  ' 

IS 

37.40 

15.68 

14.41 

:0.92 

0.98 

Normal 

1? 

46.07 

2.44 

30.97 

:1.27 

5.45 

Chloroform 

18 

37.05 

10.60 

21.06 

1:2.00 

Chloroform 

24 

40.26 

21.82 

18.45 

1:0.84 

l'.04 

the  caseoses  and  peptones  increase  for  some  months 
and  then  decrease.  In  a  chloroformed  cheese,  the  dif- 
ferent classes  of  compounds  under  discussion  all  in- 
crease continuously  from  the  beginning  for  two 
years  and  more.  In  normal  cheese,  traces  of  am- 
monia appear  at  an  early  stage  of  ripening,  while,  in 
chloroformed  cheese,  the  first  traces  usually  appear 


CAUSES    OF    RIPENING    CHANGES  371 

only  after  the  lapse  of  about  one  year,  a*id  the  increase 
is  so  very  slow,  that  even  after  two  years,  only  minute 
amounts  are  present.  From  these  results,  it  apfpears 
that  while  galactase  performs  important  work  in  the 
ripening  of  cheese,  it  cannot  be  the  chief  factor  in  this 
process,  because  its  action  produces  amino  acids  only 
very  slowly,  and  ammonia  practically  not  at  all  within 
the  normal  lifetime  of  cheddar  cheese. 

One  of  the  properties  of  galactase  is  its  sensitive- 
ness to  acids.  In  milk  containing  0.15  per  cent  of 
hydrochloric  acid,  the  galactase  is  much  less  active 
than  in  milk  containing  less  acid.  In  the  work  done 
at  the  New  York  experiment  station,  the  addition  of 
as  much  as  0.2  per  cent  of  acid  materially  increased 
the  amount  of  soluble  protein  compounds  in  cheese. 
Thus,  cheese  made  with  no  acid  had  not  ripened  at  all 
in  3  months,  while  cheese  made  with  acid  under  con- 
ditions otherwise  the  same,  contained  32.37  per  cent 
of  its  nitrogen  in  soluble  form  in  3  months.  This  fact 
also  is  not  consistent  with  the  belief  that  galactase 
is  the  chief  agency  in  the  process  of  cheese-ripening. 

ACTION  OF  MICRO-ORGANISMS  IN 
CHEESE-RIPENING 

We  come  now  to  a  consideration  of  the  fourth  and 
last  agency  which  has  been  assigned  as  one  of  the 
causes  of  the  chemical  changes  in  the  ripening  of  ched- 
dar cheese,  micro-organisms.  Although  we  discuss 
this  subject  last,  it  was,  in  point  of  time,  the  first  to 
be  studied.  When  the  subject  of  cheese-ripening  was 
first  taken  up  for  serious  study,  it  was  thought  that 
the  whole  process  was  due  to  the  action  of  bacteria, 
and  all  efforts  were  confined  to  this  single  line  of 


SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

investigation  for  years,  to  the  neglect  of  all  other 
possibilities.  The  general  statement  of  this  theory  is 
that  the  changes  observed  in  proteins  during  the 
cheese-ripening  process  are  caused  by  the  direct  action 
of  micro-organisms.  This  has  appeared  in  many  dif- 
ferent forms  according  to  the  particular  kind  of  micro- 
organisms to  which  the  work  was  attributed.  Of  the 
different  micro-organisms  assigned  as  the  cause  of 
cheese-ripening,  we  can  mention  only  one,  the  lactic 
acid  organisms.  Freudenreich  has  been  the  most 
prominent  champion  of  this  explanation  of  the 
changes  in  cheese-ripening,  and  he  devoted  years 
of  investigation  to  the  lactic  acid  organisms.  In 
favor  of  this  particular  theory,  we  have  the  fol- 
lowing facts :  ( i )  The  lactic  acid  species  of  bacteria 
are  abundant  from  the  start  and  increase  in  num- 
bers enormously  for  some  time,  suppressing  the 
growth  of  those  bacteria  that  are  known  to  have 
the  power  of  transforming  milk-casein  and  the 
paracasein  of  cheese-curd  into  soluble  products. 
(2)  There  is  a  coincidence  in  time  between  the 
early  marked  advance  in  the  formation  of  soluble 
proteins  and  the  period  of  bacterial  increase.  Against 
this  theory  we  have  the  following  facts:  (i)  The 
lactic  acid  bacteria  that  are  most  useful  in  cheese- 
making  have  not  been  satisfactorily  shown  to  have 
the  power  of  changing  milk-casein  or  paracasein  into 
soluble  products.  (2)  Ammonia  is  found  at  an  early 
stage  of  cheese-ripening,  but  it  has  not  been  proved 
that  lactic  acid  organisms  produce  ammonia.  (3)  A 
large  proportion  of  the  chemical  changes  in  cheese 
proteins  appear  after  the  lactic  acid  bacteria  have 
greatly  decreased  in  number.  This  has  been  explained 
by  saying  that  the  bacteria  secrete  an  enzym  which 


CAUSES    OF    RIPENING    CHANGES  373 

digests  cheese  proteins,  and  this  continues  the  work 
long  after  the  bacteria  themselves  disappear.  The 
existence  of  such  enzyms  from  such  a  source  has  not 
been  satisfactorily  proved  yet.  The  weight  of  evi- 
dence up  to  the  present  time  appears  to  indicate  that 
the  chief,  if  not  the  only,  work  of  the  lactic  acid  bac- 
teria is  completed  when  milk-sugar  has  been  changed 
into  lactic  acid. 

We  may  ask  here,  What  justification  have  we  for 
the  germ  theory  in  general?  (i)  It  has  been  shown 
that  various  germs  found  in  cheese  have  the  power 
to  cause  in  milk-casein  and  paracasein  changes  much 
like  those  observed  in  cheese.  (2)  Cheese-curd, 
treated  with  germicides,  fails  to  ripen.  (3)  Milk, 
sterilized  and  made  into  sterile  cheese,  does  not  ripen. 
Apparently,  there  is  no  ripening,  at  least  nothing 
like  complete  ripening,  when  there  are  no  micro- 
organisms in  cheese.  The  relations  of  certain 
micro-organisms  to  certain  kinds  of  cheese,  espe- 
cially of  the  soft  type,  have  been  satisfactorily  worked 
out,  but  the  relations  to  hard  types  of  cheese, 
like  the  cheddar,  are  far  from  being  satisfactorily 
known. 

In  going  over  the  results  of  investigations  that  bear 
on  the  subject  of  cheddar  cheese-ripening,  we  have 
seen  ( I )  that  lactic  acid  bacteria  do  an  important  and 
necessary  work  in  changing  milk-sugar  into  lactic 
acid,  which  reacts  with  calcium  salts  in  the  milk,  form- 
ing neutral  calcium  lactate  and  acid  calcium  phos- 
phate. (2)  We  have  seen  that,  in  the  presence  of  the 
acid  medium  thus  furnished  by  the  action  of  lactic  acid 
bacteria,  the  peptic  enzym  contained  in  rennet  is  able 
to  bring  about  quite  extensive  chemical  changes  in  the 
protein  of  the  curd  or  green  cheese,  forming  such 


374    SCIENCE    AND   PRACTICE    OF    CHEESE-MAKING 

compounds  as  paranuclein,  caseoses  and  peptones  and 
much  smaller  proportions  of  amino  acids  and  little  or 
no  ammonia.  (3)  Galactase  is  able  to  .perform  chem- 
ical work  similar  in  character  to  that  of  rennet-pepsin, 
but  how  much  insoluble  protein  it  can  render  soluble 
in  a  given  period  of  time,  we  do  not  know.  (4) 
None  of  the  three  agencies  previously  mentioned  has 
the  power  of  forming  ammonia,  as  found  in  normal 
cheese-ripening.  It,  therefore,  appears  that  bacteria 
alone  must  be  responsible  for  the  production  of  am- 
monia and  of  a  large  proportion  of  the  amino  acids. 

It  is  obvious  that  the  process  of  cheese-ripening  is 
not  as  simple  as  was  once  believed,  but,  on  the  con- 
trary, is  exceedingly  complex.  We  cannot  say  yet 
just  what  part  each  agent  plays  nor  to  what  extent 
each  is  independent  of,  or  dependent  upon,  the  others. 
For  example,  the  digesting  action  of  rennet  is  clearly 
dependent  upon  acidity.  Does  the  action  of  rennet 
have  anything  to  do  with  the  changing  of  the  in- 
soluble curd  into  a  brine-soluble  substance  and  back 
again  into  a  substance  insoluble  in  brine?  Or  are 
these  changes  immediately  dependent  upon  acid-form- 
ing bacteria?  Does  the  rennet  have  any  digesting 
effect  until  the  brine-insoluble  form  of  protein  ap- 
pears? What  forms  of  cheese  proteins  can  galactase 
or  other  milk  enzyms  attack  and  under  what  condi- 
tions of  acidity,  temperature,  etc.?  When  do  the 
bacteria  begin  their  work  in  rendering  soluble  the 
insoluble  cheese  proteins?  Or  do  they  act  only  upon 
the  products  formed  by  rennet  or  galactase?  Is  the 
bacterial  work  confined  to  one  specific  micro-organism, 
or  is  the  work  associative? 

We  thus  see  that  there  are  many  details  still  un- 
settled; but,  in  view  of  what  we  think  we  know  now, 


CAUSES    OF   RIPENING    CHANGES  375 

we  are  justified  in  believing  that  the  chemical  changes 
of  cheese-ripening  are  the  result  of  several  different 
kinds  of  fermentative  agents,  the  precise  relations  of 
each  of  which  to  the  details  of  the  ripening  process 
have  not  been  satisfactorily  worked  out  yet. 

CHEESE  FLAVORS 

In  connection  with  the  ripening  of  cheese,  the  ques- 
tion of  cheese  flavor  is,  of  course,  one  of  paramount 
importance.  What  do  we  know  about  the  origin  of 
cheese  flavor,  the  particular  substance  or  compound 
that  the  flavor  comes  from,  and  the  method  of  its 
formation  ?  Very  little,  in  detail.  When  we  speak 
or  think  of  flavors  in  cheese,  we  too  commonly  view 
them  in  a  vague,  misty  and  mysterious  way.  As  a 
matter  of  fact,  flavors  are  realities,  and  sometimes 
very  striking  ones,  and  they  come  from  real  things. 
Every  flavor  represents  one  or  more  specific  chemical 
compounds.  Some  one  chemical  compound,  or,  it 
may  be,  some  mixture  of  two  or  more  definite 
chemical  compounds,  is  entirely  responsible  for 
each  and  every  flavor  found  in  cheese,  or,  for  that 
matter,  anywhere  else,  whether  pleasant  or  other- 
wise. 

The  study  of  the  problem  of  cheese  flavors  has 
received  less  attention  than  that  of  the  chemical 
changes  in  cheese  proteins,  though  the  two  questions 
are  probably  closely  related.  The  questions  that 
present  themselves  in  connection  with  the  normal 
flavors  of  American  cheddar  cheese  are:  (i)  What 
are  they?  (2)  Where  do  they  come  from?  (3) 
What  produces  them  or  what  is  the  manner  of  their 
formation  ? 


376     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKIXG 

The   following   facts   have   some  bearing   on  these 
questions : 

(1)  Newly  made  cheese  has  no  real  cheese  flavor. 

(2)  Some   days  or  weeks  must  pass  before  real 
cheese  flavor  begins  to  appear. 

(3)  The  breaking  down  of  the  proteins  contained 
in  the  cheese-curd  and  green  cheese,  resulting  in  the 
formation  of   water-soluble   protein    derivatives,   pre- 
cedes, to  some   extent,   the  appearance   of   flavor   in 
cheese. 

(4)  Cheese  flavors  are  produced  by  some  chemical 
change  in  some  compound  or  compounds  present  in 
green  cheese. 

(5)  In  experiments  where  bacterial  action  is  pre- 
vented, we  do  not  find  cheese  flavor. 

(6)  Neither  galactase  nor  rennet  nor  pepsin  ap- 
pears to  be  able  to  produce  compounds  that  have  any 
flavor  at  all. 

(7)  Flavor  develops  more  quickly  at  higher  than 
at  lower  temperatures. 

(8)  Flavor  develops  more  rapidly  in  a  moist  than 
in  a  dry  cheese. 

(9)  Many  of  the  abnormal  flavors  of  cheese  can 
be  traced  directly  to  specific  micro-organisms.     For 
example,  the  offensive  odor,  usually  characterized  as 
"taint,"  is  traced  to  a  gas-producing  organism  closely 
related  to  Bacillus  coli  communis,  a  species  of  bacteria 
commonly  found  in  the  intestinal  tract. 

(10)  Bitter  flavor   in   cheese   has   been   identified 
as  a  compound  formed  from  acetaldehyd   (produced 
by  the  alcoholic  fermentation  of  milk-sugar)  and  am- 
monia, the  product  of  bacterial  action. 


CAUSES    OF    RIPENING    CHANGES  377 

(n)  The  flavoring  substance,  whatever  it  is,  is 
present  in  extremely  small  amounts 

(12)  A  cheesy  flavor  often  develops  in  butter  that 
is  not  kept  at  sufficiently  low  temperature.  A  distinct 
cheesy  flavor  is  common  in  kumiss,  when  it  is  one  o«- 
two  weeks  old. 

What  suggestions  can  we  derive  from  the  preceding- 
statements  ? 

(1)  It  is  quite  possible  that  the  particular  com- 
pounds which  furnish  cheese  flavor  are  certain  pro- 
tein derivatives  that  are  formed  only  after  the  lapse 
of  some  time  and  are  much  simpler  than  the  principal 
protein  found  in  the  green  cheese.    This  suggestion  is 
supported   by  certain   facts,     (a)    Cheese   flavors    do 
not  appear  until   these   simpler   compounds  begin   to 
be  formed,     (b)    Such  compounds  are  known  to  be 
capable  of  furnishing  flavors,     (c)  Extremely  minute 
quantities  of  such  substances  go  a  long  way  in  pro- 
viding flavor.     Owing  to  the  extremely  minute  quan- 
tities   of    such    compounds    present,    the    problem   of 
isolating  and  identifying  them  is  one  of  great  diffi- 
culty. 

(2)  We  find  that,  in  cheese  cured  at  low  tempera- 
tures, we  have,  in  general,  about  the  same  kinds  of 
compounds  as  in  cheese  cured  at  higher  temperatures, 
but  the  chemical  changes  have  not  gone  quite  so  fast 
and  we  have  smaller  quantities  of  these  compounds 
formed  that  produce  flavor.     This  is  in  full  agreement 
with   the    characteristic    mild   flavor   of   cold-ripened 
cheese. 

(3)  In  old  cheese,  characterized  by  very  strong 
flavor,    especially   a   pungent   odor   and   biting   taste, 
ammonia  is  always  present  in  large  quantities  as  com- 


SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


pared  with  mild-flavored  cheese.     The  pungent  flavors 
are  due  to  ammonia  compounds. 

(4)  As  to  the  material  source  of  flavoring  com- 
pounds in  cheese,  it  is  quite  probable  that  they  come 
from  the  changing  of  paracasein   into   simpler   com- 
pounds, especially  such  compounds  as  amino  acids  and 
ammonia. 

(5)  Fat  was  formerly  regarded  as  the  sole  source 
of  flavor  in  cheese,  and  in  butter  also.     It  is  true  that 
when  fat  in  cheese  decomposes,  it  may  form  a  variety 
of  flavoring  substances,  such,  for  example,  as  butyric 
acid,   the   characteristic   flavor   of   rancid   cheese   and 
butter;    but  such  flavors  are  offensive.     Fat  in  ched- 
dar  cheese  does  not  appear  to  undergo  any  appreciable 
change  in  the  early  stages  of  cheese-ripening,  espe- 
cially when  cheese  is  ripened  under  proper  conditions 
of  temperature.     The  decomposition  of  fat  which  gives 
rise  to  the  small  white  specks  sometimes  observed  in 
cheese  ripened  at  low  temperature  does  not  affect  the 
flavor  in  any  way. 

(6)  What  is  the  probable  cause  of  formation  of 
cheese-flavoring  compounds?     It'  is   well-known   that 
the  action  of  certain  bacteria  is  responsible  for  many 
of  the  bad  flavors  of  cheese.     Up  to  the  present  time, 
we  are  unable  to  find  any  satisfactory  cause  other  than 
micro-organisms  for  the  real,  desirable  cheese  flavor; 
because,  in  the  absence  of  living  organisms  or  of  the 
enzyms  secreted  by  them,  we  get  no  flavor. 


CHAPTER  XXVI 

Commercial  Relations  of  Cheese-Ripening 

In  the  three  chapters  preceding,  we  have  considered 
cheese-ripening  in  relation  to  (i)  the  conditions  that 
affect  the  loss  of  weight  during  the  ripening  process, 
(2)  the  chemical  changes  taking  place,  and  (3)  the 
causes  of  the  changes  that  occur  in  the  process.  In- 
cidentally, we  have  touched  upon  some  of  the  practical 
relations  of  the  results,  but  have  reserved  for  a 
separate  chapter  a  more  detailed  discussion  of  the 
commercial  aspects  of  cheese-ripening.  We  propose 
now  to  take  up  for  more  extended  treatment  some 
of  the  practical  applications  of  the  results  of  investiga- 
tion and  shall  consider  the  following  subjects:  (i) 
Extent  of  ripening  losses  at  cheese-factories,  (2) 
value  of  water  in  cheese  to  dairymen,  (3)  moisture 
in  cheese  in  relation  to  commercial  quality,  (4)  the 
proper  percentage  of  moisture  in  cheese,  (5)  value  of 
water  in  cheese  to  consumers,  (6)  the  reduction 
of  ripening  losses  in  commercial  investigations,  (7) 
the  relation  of  conditions  of  ripening  to  the  quality 
of  cheese,  (8)  the  effects  of  freezing  on  quality  of 
cheese,  (9)  financial  application  of  results  of  cheese- 
ripening  investigations. 

FACTORY  LOSSES  IN  RIPENING 

From  inquiries  made  among  cheese-makers  several 
years  ago,  we  found  quite  a  variation  in  respect  to 
the  loss  of  moisture  experienced  by  them  in  ripening 

379 


SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

cheese.  One  of  the  most  complete  records,  covering 
an  entire  season,  furnished  by  a  cheese-maker  and 
factory  owner  who  has  better  than  average  conditions 
in  his  curing-rooms,  made  the  average  loss  of  weight 
during  30  days  amount  to  about  5  oounds  per  100 
pounds  of  cheese.  Others  reported  an  average  loss 
for  the  first  30  days  as  high  as  10  pounds  per  100 
pounds  of  cheese.  The  average  loss  was  somewhere 
between  these  two  extremes,  probably  not  far  from  7 
pounds  per  100  pounds  of  cheese.  In  many  fac- 
tories, conditions  have  not  improved  since  the 
inquiry  was  made. 

VALUE  OF  WATER  IN  CHEESE  TO  DAIRY- 
MEN 

To  the  cheese-maker  and  producer  of  milk,  water 
in  cheese  is  money  when  put  there  in  the  right  way 
and  in  the  proper  proportions.  It  is  essential,  in  the 
process  of  manufacture,  to  incorporate  water  in  cheese 
in  quantities  best  suited  to  the  requirement  of  the 
market  for  which  the  cheese  is  intended,  and  then  it 
is  equally  essential  that  the  water  be  kept  there  with 
the  least  possible  loss.  From  the  dairymen's  stand- 
point, it  is  desirable  to  sell  as  much  water  in  cheese 
as  will  suit  the  consumer.  In  preventing  excessive 
loss  of  moisture,  there  is  more  water  to  sell  at  cheese 
prices,  and  at  the  same  time  a  resulting  product  that 
suits  the  consumer  better.  In  the  conditions  prevail- 
ing in  many  factories,  high  temperatures  which  cause 
increased  loss  of  moisture  also  cause  loss  of  fat  by 
exudation  from  the  surface  of  the  cheese.  At  75°  F. 
and  above,  this  loss  becomes  considerable.  It  has  been 
shown  that  the  loss  of  moisture  in  curing-rooms  can 


COMMERCIAL   CHEESE-RIPENING  381 

be  reduced  to  4  pounds  per  100  pounds  of  cheese  under 
conditions  practicable  at  factories.  Using  this  figure 
as  a  basis  for  calculation,  we  find  that,  for  every  100 
pounds  of  cheese,  an  average  of  3  pounds  of  water 
could  be  saved  to  sell  at  cheese  prices.  This  would 
mean  an  average  increase  of  30  cents,  received  for 
every  100  pounds  of  cheese.  This  would  mean  an 
average  saving  of  $300  a  season  for  a  factory  with 
a  total  season's  output  of  100,000  pounds  of  cheese. 
One  cheese-maker  reports  that  he  calculated  one  sea- 
son's loss  from  shrinkage  and  found  it  over  $600. 
While  such  losses  may  not  be  regarded  as  large  in 
comparison  with  the  total  receipts,  they  constitute  a 
noticeable  percentage  when  viewed  as  unnecessary 
decrease  of  profits,  and  are  well  worth  saving. 

MOISTURE  IN  CHEESE  IN  RELATION  TO 
COMMERCIAL  QUALITY 

We  have  just  called  attention  to  increased  re- 
ceipts coming  from  cheese,  as  a  result  of  preventing 
excessive  loss  of  moisture.  Such  saving  of  moisture 
not  only  increases  the  amount  of  cheese  to  be  sold 
but  also  increases  the  value  of  the  cheese  from  the 
standpoint  of  commercial  quality. 

The  relations  existing  between  moisture  and  flavor 
are  known  only  in  a  very  general  way.  But  we  know 
something  of  the  general  relation  between  moisture 
and  texture.  Excessive  moisture  produces  a  degree 
of  softness,  which  is  undesirable,  from  a  commercial 
standpoint,  and  at  ordinary  temperatures  favors  the 
formation  of  holes,  a  serious  fault  in  the  texture  of 
cheddar  cheese  intended  for  export  trade.  On  the 
other  hand,  deficient  moisture  favors  the  production 


382     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

of  a  crumbly,  dry,  mealy  body,  which  is  an  undesir- 
able condition.  High  temperatures  cause  excessive 
loss  of  moisture  and  result  in  the  production  of 
a  crumbly  body.  This  condition  injures  the  commer- 
cial quality  of  cheese  and  results  in  lower  prices  for 
such  cheese.  The  following  table  illustrates,  in  a 
practical  way,  the  effect  of  different  temperatures 
upon  texture  and  moisture: 


EFFECT   OF   TEMPERATURE   OF   CURING  ON   TEXTURE  AND 
MOISTURE   OF   CHEESE 


Temperature  of 
curing-room 

Texture  of  cheese 
(Perfect  texture  is  25) 

Moisture  lost  by  100 
pounds  of  cheese 

55°F. 
60°F. 
65°F. 
70°F. 
75°F. 
80°F. 

24.6 
24.4 
23.6 
22.0 
21.4 
20.6 

Lbs. 
8.5 
9.0 
9.2 
10.2 
10.7 
13.1 

WHAT     PERCENTAGE     OF    MOISTURE 
SHOULD   CHEESE   HAVE? 

Much  of  the  cheese  made  in  New  York  contains, 
in  the  fresh  state,  from  36  to  37.5  per  cent  of  water. 
The  home-trade  cheese,  much  of  which  is  made  in  the 
fall,  contains  38  to  40  per  cent  of  water.  For  the 
average  consumer,  it  is  safe  to  say,  the  amount  of 
moisture  in  cheese  should  be  not  less  than  33  to  35 
per  cent  at  the  time  of  consumption.  Taking  every- 
thing into  consideration,  it  is  reasonable  to  expect 
better  results  in  reference  to  quality  by  holding  a 
moderate  amount  of  moisture  in  the  green  cheese  and 
so  ripening  as  to  lose  only  a  small  amount  of  water, 


COMMERCIAL   CHEESE-RIPENING  383 

than  by  holding  an  excessive  amount  of  moisture  in 
the  green  cheese  and  so  ripening  as  to  lose  a  larger 
amount  of  moisture.  Some  cheese-makers  expect  that 
they  must  lose  10  pounds  of  weight  per  100  pounds 
of  cheese  in  ripening,  and  they  attempt  to  meet  this 
loss  by  retaining  40  per  cent  or  more  of  moisture  in 
the  cheese.  Such  a  practice  cannot  lead  to  good  re- 
sults from  any  point  of  view. 

A  fact  that  should  not  be  lost  sight  of  in  this  con- 
nection is  this :  Cheese  ripened  at  such  low  tempera- 
tures as  are  favorable  to  diminishing  the  loss  of 
moisture  can  carry  larger  amounts  of  moisture  from 
the  start  without  impairing  the  quality 

VALUE  OF  WATER  IN  CHEESE  TO 
CONSUMERS 

In  the  first  place,  cheese  that  has  not  lost  too  much 
of  its  moisture  is  more  pleasing  to  the  taste  of  the 
average  consumer.  In  the  next  place,  the  more  com- 
pletely a  cheese  dries  out,  the  harder  and  thicker  is 
the  rind  and  the  greater  the  loss  to  the  consumer. 
Most  people  have  become  accustomed  to  such  a  waste, 
but  much  of  it  is  unnecessary.  In  a  carefully  ripened 
cheese,  the  rind  is  comparatively  moist  and  only  a  very 
thin  portion  need  be  lost,  and  even  this  can  be  used 
in  cooking. 

REDUCTION  OF  RIPENING  LOSSES  IN 
COMMERCIAL  INVESTIGATIONS 

In  1902-3  an  investigation,  on  a  commercial  scale, 
was  undertaken  by  the  Dairy  Division  of  the  Bureau 
of  Animal  Industry,  United  States  Department  of 


384     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

Agriculture,  in  co-operation  with  the  experiment  sta- 
tions of  Wisconsin  and  New  York,  in  which  cheese 
was  ripened  at  40°,  50°  and  60°  F.,  some  being  cov- 
ered with  paraffin.  In  1903-4  the  Dairy  Division 


FIG.  47 — A  WEEK'S  TEMPERATURE  RECORD  OF  A  CURING-ROOM 

HELD   AT    50°F 

repeated  the  work,  but  used  a  lower  range  of 
temperatures,  28°,  34°  and  40°  F.,  and,  in  one  case, 
5°  F.  The  object  of  these  investigations  was  to 
study  on  a  commercial  scale,  under  commercial  con- 
ditions, (l)  the  influence  which  different  tempera- 
tures have  upon  (a)  the  loss  of  weight  in  cheese,  and 


m 


FIG.  48-TEMPERATURE 
RECORD  COVERING  SEV- 
ERAL MONTHS  IN  CASE 
OF  CURING  -  ROOMS 
HELD  AT  28°  AND 
40°  F, 


(b)  the  commercial  qualities  of 
the  cheese;  and  (2)  the  in- 
fluence of  covering  cheese  with 
paraffin  upon  (a)  the  loss  of 
weight  in  cheese,  and  (b)  the 
commercial  qualities  of  the 
cheese,  when  kept  at  different 
temperatures. 

In  the  different  sets  of  ex- 
periments, the  cheeses  used 
were  of  the  following  sizes: 
(l)  Cheddars,  65-70  pounds;  (2) 
Cheddars,  40-45  pounds;  (3) 
Flats  or  Twins,  30-35  pounds; 
(4)  Daisies,  20  pounds;  (5) 
Young  Americas,  10  to  12% 
pounds ;  (6)  Prints,  10  pounds. 

The  experiments  were  be- 
gun in  October  and  extended 
through  periods  of  time  lasting 
20  to  35  weeks.  The  cheeses 
were  obtained  direct  from  fac- 
tories in  New  York,  Pennsyl- 
vania, Ohio,  Michigan,  Illi- 
nois, Wisconsin  and  Iowa.  They 
were  10  to  15  days  old  when 
placed  in  storage.  In  most 
cases  they  represented  the 
cheddar  type  manufactured  for 
export  trade,  close-textured, 
firm-bodied  and  long-keeping. 
In  some  cases  the  Michigan 
type  was  used,  which  is  char- 
acterized as  ^soft-bodied,  of  high 
water  content,  more  or  less 

386 


386     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

porous  and  poor  in  keeping  quality.  Another  type 
represented  was  the  sweet-curd,  more  or  less  inter- 
mediate in  qualities  between  the  cheddar  and  the 
Michigan  home-trade  types. 

The  cheeses  were  placed  in  storage  during  the  ex- 
periments where  the  temperature  could  be  very  closely 
kept  under  control.  Various  devices  and  records  are 
in  use  for  ascertaining  the  uniformity  of  the  tempera- 
ture from  day  to  day.  Two  different  forms  of  records 
are  given  in  Figs.  47  and  48. 

It  is  not  practicable  to  present  the  detailed  results 
of  the  different  experiments;  we  must  limit  our  con- 
sideration to  a  general  summary  of  the  results.  We 
shall  present  the  results  relating  to  the  losses  of  ripen- 
ing under  the  following  subdivisions  :  ( I )  Tempera- 
ture, (2)  size  of  cheese,  (3)  type  of  cheese,  and  (4) 
coating  with  paraffin. 

Influence  of  temperature  on  loss  of  weight. — The 
results  of  the  various  investigations  agree  in  the  fol- 
lowing respects :  ( i )  The  cheese  continued  to  lose 
weight  in  nearly  every  case  as  long  as  weighings  were 
made  (about  250  days),  this  being  true  at  all  tem- 
peratures employed  (28°-6o°  F.).  (2)  The  loss  of 
weight  was  least  at  the  lowest  temperature  (28°  F.) 
and  increased  with  rise  of  temperature.  This  can  be 
illustrated  in  case  of  the  65~7o-pound  cheddars,  as 
follows : 


POUNDS   OF  WEIGHT  LOST  FOR    IOO  POUNDS  OF  CHEESE 
STORED  AT 


28°F. 

34°F. 

40°F. 

50°F. 

60°F. 

27  weeks  .  . 

1.81 

*   4.18 

4.68 

6.00 

9.90 

35  weeks  

2.88 

5.12 

5.87 

COMMERCIAL   CHEESE-RIPENING 


At  the  end  of  27  weeks,  the  loss  of  weight  was  more 
than  3  times  as  great  at  40°  F.  as  at  28°  F.,  and  about 
5  times  as  great  at  60°  F.  as  at  28°  F.  At  the  end  of 
35  weeks,  the  loss  at  40°  F.  was  just  twice  as  great  as 
at  28°  F. 

Influence  of  size  of  cheese  in  loss  of  weight. — 
Small-sized  cheeses,  other  conditions  being  the  same, 
lost  a  larger  amount  of  moisture  than  large  cheeses. 
This  tendency  is  shown  at  different  temperatures  by 
the  following  tabulated  statement: 

WEIGHT  LOST  PER   IOO  POUNDS  OF  CHEESE  IN  2O  WEEKS 


Average  weight 
of  cheese 

At  40°F. 

At  50°F. 

At  60°F. 

Pounds 

Pounds 

Pounds 

Pounds 

70 

2.5 

2.4 

4.2 

45 

2.7 

3.7    • 

5.1 

35 

3.9 

5.9 

8.5 

12J 

4.6 

8.1 

12.0 

The  variation  in  loss  between  different  sizes  is  much 
less  at  lower  than  at  higher  temperature. 

Influence  of  type  of  cheese  on  loss  of  weight. — 
Firm-bodied,  close-textured  cheese  loses  water  less 
rapidly  than  soft-bodied,  open-textured  cheese  (p.  324). 

Influence  of  paraffin  coating  on  loss  of  weight. — 
Cheese  covered  with  paraffin  loses  less  weight  than 
cheese  not  so  coated.  By  covering  cheese  with 
paraffin,  a  saving  in  loss  of  weight  can  be  effected 
amounting  to  5-  or  6  pounds  per  100  pounds  of  cheese 
at  60°  F.;  and  at  50°  F.  or  below  the  total  loss  of 
weight  can  be  reduced  to  I  or  2  pounds  per  100 
pounds  of  cheese  in  the  ordinary  period  of  ripening. 
At  40°  F.,  the  loss  in  case  of  the  large-sized  ched- 
dar  was  reduced  about  one-half,  as  compared  with 


388     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

cheese  not  coated;  at  34°  F.,  nearly  three-fourths  of 
the  loss  was  prevented;  at  28°  F.,  the  losses  were 
very  slight,  only  a  little  over  j£  pound  in  27  weeks. 
The  use  of  paraffin  coating  makes  a  greater  propor- 
tionate saving  in  small  cheeses  than  in  large  ones.  In 
the  case  of  the  Young  America  cheeses,  the  loss  at 
40°  F.  was  reduced  to  about  one-fourth  of  what  it 
was  when  the  cheese  was  uncoated 

RELATIONS  OF  CONDITIONS  OF  RIPENING 
TO  QUALITY  OF  CHEESE 

In  all  the  experiments  mentioned,  carefully  selected 
experts  judged  the  cheese  from  a  commercial  stand- 
point and  scored  them.  These  examinations  were 
made  at  regular  intervals  during  the  continuation  of 
the  experiments.  The  results  will  be  considered  with 
reference  to  the  effect  of  (i)  temperature,  (2)  coat- 
ing with  paraffin. 

Influence  of  temperature  on  quality. — Below  40° 
F.,  and  down  to  28°  F.,  the  temperature  does  not 
appear  to  have  any  marked  effect  upon  the  commercial 
quality  of  cheese.  Cheese  ripened  at  40°  was  superior, 
almost  without  exception,  to  cheese  ripened  at  higher 
temperatures.  The  following  figures  show  the  aver- 
age scores  at  different  temperatures: 


Temperature  Score 

40°F.                                        95.7 

50°F                                                                94,2 

60°F.                                                                                      91.7 


There  was  more  marked  deterioration  in  quality 
between  50°  and  60°  F.  than  between  40°  and  50°  F. 
In  general,  the  higher  the  temperature,  the  greater  is 


COMMERCIAL    CHEESE-RIPENING 


the  relative  deterioration  of  cheese  in  quality  for  each 
degree  of  temperature. 

The  following  figures  demonstrate  that  the  dif- 
ference in  quality  falls  mostly  on  the  flavor  (50, 
perfect),  and  to  a  less  extent  on  texture  and  body 
(25,  perfect)  : 


Qualities 

At  40°F. 

At  50°F. 

At  60°F. 

Flavor                 

47  4 

46  4 

44  8 

Body  and  texture  

23.4 

23.0 

22.2 

At  any  given  time,  the  cheese  ripened  at  40°  F.  was 
usually  better  in  quality  than  that  at  50°  F.,  and  that 
at  50°  F.  was  better  than  that  at  60°  F.  The  longer 
the  time  of  ripening,  the  greater  was  the  difference  in 
favor  of  the  lower  temperatures,  as  illustrated  in  the 
following  table: 


Age  of  cheese 

Score  at  40°F. 

Score  at  50°F. 

Score  at  60°P. 

Weeks 

10 

96.3 

94.7 

92. 

20 

93.8 

91.5 

89.7 

28 

94.2 

91.9 

35 

95.3 

... 

The  cheese  cured  at  60°  F.  showed  such  deteriora- 
tion of  quality  in  20  weeks  that  it  was  sold  in  order 
to  prevent  complete  loss. 

Influence  of  paraffin  coating  on  quality. — The 
effect  of  covering  cheese  with  paraffin  was,  in  several 
cases,  to  improve  the  quality  of  the  cheese  so  covered. 
The  difference  was  more  marked  at  60°  F.  than  at 
lower  temperatures.  The  cheese  coated  with  paraffin 


39O     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

and  ripened  at  40°  gave  its  highest  score  at  the  end 
of  35  weeks.  In  no  case  did  the  cheese  coated  with 
paraffin  show  any  depreciation  in  quality  as  compared 
with  cheese  not  so  covered.  These  results  are  in  har- 
mony with  what  one  might  reasonably  predict.  Any 
condition  which  maintains  in  the  cheese  the  uniformity 
of  the  moisture,  when  not  in  excess,  favors  the>  normal 
ripening  changes. 

The  finish  of  cheese  was  greatly  improved  by  a 
coating  of  paraffin,  since  the  growth  of  molds  is  pre- 
vented. In  every  case  cheeses  covered  with  paraffin 
were  entirely  clean,  while  the  others  were  more  or 
less  heavily  coated  with  molds. 


FIG.  49 — SECTION  OF  FROZEN  CHED- 
DAR CHEESE  AFTER  STORAGE  5l/2 
MONTHS  AT  5°  F. 

THE  EFFECTS  OF  FREEZING  ON  QUALITY 
OF  CHEESE 

Cheese  placed  in  a  room  kept  at  5°  F.  was  im- 
mediately frozen  hard.  After  a  time  the  ends  and 
sides  appeared  to  be  lumpy,  due  to  the  expansion  of 
the  frozen  water  in  the  cheese.  After  being  6  months 
in  a  frozen  condition,  the  cheese  was  slowly  thawed 


COMMERCIAL   CHEESE-RIPENING 


391 


and  examined.  When  freshly  cut,  the  appearance  was 
normal,  but  the  surface  dried  out  more  rapidly  than 
in  normal  cheddar  cheese.  The  body  was  crumbly,  as 
in  the  case  of  a  cheese  deficient  in  water.  Little  or  no 
ripening  had  taken  place  and  such  insipid  flavor  as 
there  was  did  not  resemble  anything  normal.  The 
frozen  cheese  also  showed  a  mottled  appearance,  net 
shown  by  any  other  cheese  ripened  at  28°  F.  or  above. 
Fig.  49  shows  the  appearance  of  a  cheese  after  being 
kept  at  5°  F.  for  several  months. 

FINANCIAL    APPLICATION    OF    RESULTS 
OF  CHEESE-RIPENING  INVESTIGATIONS 

Any  reduction  in  loss  of  weight  or  any  improve- 
ment in  quality  in  cheese-ripening  means  an  increase 
of  money  that  can  be  realized  in  the  sale  of  cheese. 
We  have  seen  that  the  curing  of  cheese  at  tempera- 
tures as  low  as  40°  F.  has  the  effect  of  ( I )  preventing 
loss  of  moisture  and  (2)  increasing  the  value  of  the 
cheese.  Therefore,  we  not  only  have  more  cheese  to 
sell  but  can  sell  it  at  a  higher  price.  Taking  cheese 
20  weeks  old  as  a  basis  for  comparison,  we  know  how 
much  weight  is  lost  at  different  temperatures  and  also 
the  difference  in  price.  From  these  figures  the  fol- 
lowing tabulated  statement  is  given : 

MONEY    RETURNS     AT     SEVERAL    TEMPERATURES 


Temperature 
of  curing 

Cured  cheese 
equivalent  to  100 
pounds  of  green 
cheese 

Market  price  of  1 
pound  of  cheese 

Receipts  from 
cheese 

Degrees  P. 
40 

50 
60 

Pounds 
96.2 
95.2 
92.2 

Cents 
13.275 
13.050 
12.675 

Dollars 
12.77 
12.42 
11.69 

392     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


These  figures  indicate  that  from  100  pounds  of  green 
cheese  put  into  the  curing-room  we  were  able  to  re- 
alize from  that  cured  at  40°  F.,  35  cents  more  than 
from  cheese  cured  at  50°  P.,  and  $1.08  more  than  from 
that  cured  at  60°  F.  From  the  cheese  cured  at  50° 
F.,  we  received  73  cents  more  for  100  pounds  than 
from  that  cured  at  60°  F. 

If,  we  compare  our  results  obtained  with  cheese  cov- 
ered with  paraffin  with  those  given  by  cheese  not  so 
covered,  we  have  the  following  tabulated  statement: 

COMPARATIVE    VALUE    OF    PARAFFINED    AND    UNPARAF- 
FINED   CHEESE 


Temper 
ature  of 
curing- 
room 

Cured  cheese 
equivalent  to  100 
pounds  of  green 
cheese 

k  Value  of  1  pound 
of  cheese 

Receipts  from 
cheese 

Paraf- 
fined 

Not  par- 
affined 

Paraf- 
fined 

Not  par- 
affined 

Paraf- 
fined 

Not  par- 
affined 

DV- 

50 
60 

Pounds 
99.7 
99.5 
98.6 

Pounds 
96.2 
95.2 
92.2 

Cents 
14.25 
14.25 
13.75 

Cents 
14.25 
14.25 
13.50 

Dollars 
14.21 
14.19 
13.56 

Dollars 
13.70 
13.56 
12.45 

At  40°  F.  the  difference  in  favor  of  the  paraffined 
cheese  is  51  cents  for  100  pounds  of  cheese  originally 
placed  in  the  curing-room;  at  50°  F.  the  difference 
is  63  cents,  and  at  60°  F.,  $1.11.  Covering  cheese 
with  paraffin  results  in  greater  saving  at  higher  tem- 
peratures than  at  lower  temperatures. 

Comparing  paraffined  cheese  cured  at  40°  F.  with 
unparaffined  cheese  cured  at  60°  F.,  we  find  a  differ- 
ence of  $1.76  for  100  pounds  of  cheese  in  favor  of 
the  paraffined  cheese  and  the  lower  temperature. 


COMMERCIAL   CHEESE-RIPENING  393 

These  experiments  demonstrate  that,  by  curing 
cheese  at  lower  temperatures  than  those  that  have 
been  commonly  in  use,  it  is  possible  to  obtain  a  perfect, 
edible  quality  of  cheddar  cheese,  which  means  cheese 
of  clean,  mild,  delicate  flavor,  somewhat  lasting,  but 
not  so  sharp  as  to  bite  the  tongue ;  and  body  such 
that  a  piece  of  cheese  on  the  tongue  dissolves  com- 
pletely, leaving  only  a  sensation  of  smoothness  and 
richness,  with  no  trace  of  harshness  or  grittiness. 
Such  cheese  can  be  eaten  without  the  disagreeable 
effect  of  long  after-tasting,  which  imperfectly  cured 
cheese  produces.  The  consumption  of  cheese  can  be 
greatly  stimulated  by  making  the  cheese  right  and 
then  ripening  it  under  proper  conditions  of  tempera- 
ture and  moisture. 

METHODS   OF   PROVIDING   PROPER   CON- 
DITIONS FOR  CHEESE-RIPENING 

There  are  three  ways  in  which  the  evils  resulting 
from  improper  conditions  of  ripening  can  be  over- 
come: (i)  Immediate  sale  and  removal  of  cheese, 

(2)  providing  proper  conditions  in  cheese-factory  and 

(3)  central  curing-stations.     We  will  briefly  consider 
each. 

Immediate  sale  and  removal. — In  factories  which 
are  provided  with  no  adequate  facilities  for  ripening 
cheese,  it  has  in  many  cases  come  to  be  a  custom  to 
sell  the  cheese  before  it  has  had  a  chance  to  deteriorate. 
So  far  as  the  cheese-factory  is  concerned,  this  system 
relieves  it  of  responsibility  for  the  cheese  after  its 
manufacture;  but  the  factory  patrons  lose  such  ad- 
vantage as  would  come  from  providing  good  curing- 
rooms  and  holding  the  cheese.  The  buyer  has  an 


394     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

opportunity  for  any  increased  profit  that  comes  from 
ripening  the  cheese  properly;  but  too  often  he  has  no 
equipment  for  ripening  and  hastens  to  dispose  of 
the  cheese  as  quickly  as  possible.  In  such  cases  the 
cheese  is  put  before  consumers  when  it  is  still  so 
green  as  to  do  injustice  to  the  reputation  of  the  cheese- 
maker  and  the  cheese-factory.  The  most  extensive 
cheese  buyers  usually  have  cold-storage  plants  and 
hold  the  cheese. 

Providing  proper  conditions  in  cheese-factory. — 
In  many  cases,  probably  in  the  majority  of  factories, 
the  best  interests  of  the  factory  will  be  conserved  by 
providing  a  curing-room  as  a  part  of  the  factory 
equipment,  such  as  is  described  on  page  103.  This  is 
practicable,  efficient  and  economical  from  every  point 
of  view. 

Central  curing-stations. — In  Wisconsin  and  Canada 
the  problem  of  cheese-curing  has  been  solved,  to  some 
extent,  by  providing  buildings,  centrally  located  with 
reference  to  a  number  of  cheese-factories,  where  the 
cheese  are  taken  as  soon  as  practicable  and  stored 
until  sold.  Such  curing-stations  are  provided  with  a 
modern  cold-storage  equipment  and  are  able  perfectly 
to  control  conditions  of  temperature  and  humidity. 
The  cost  of  ripening  cheese  in  this  way  is  more  than 
repaid  by  the  increase  of  price  received  for  the  cured 
cheese. 


Part  IV 

Methods  of  Making  Different 
Varieties  of  Cheese : 


Stilton. 

English  Sage. 

Cottage. 

Pasteurized  Neufchatel 

Cream. 

Club. 

Edam. 

Gouda. 


CHAPTER  XXVII 

Methods  of  Making  Different  Varieties 
of  Cheese 

While  the  original  purpose  of  the  authors  was 
to  confine  the  matter  of  the  book  to  the  subject  of 
cheddar  cheese,  it  has  seemed  desirable  to  devote 
one  chapter  to  a  brief  description  of  the  methods 
of  making  some  other  varieties  of  cheese.  We  have 
chosen  for  the  most  part  those  varieties  which  can 
be  made  with  simple  equipment.  Such  varieties  as 
Swiss  cheese,  for  example,  can  not  be  properly 
treated  in  a  limited  way. 

STILTON  CHEESE 

In  England  Stilton  cheese  is  the  most  popular  of 
all  blue-mold  varieties.  In  Canada,  only  a  small 
quantity  of  Stilton  cheese  is  manufactured  and,  in  the 
United  States,  a  still  smaller  quantity. 

First  stages  of  cheese-making  process. — The 
method  of  making  modern  Stilton  cheese  does  not 
vary  greatly  in  the  early  stages  from  that  of 
cheddar  cheese-making.  Up  to  the  time  of  salting, 
the  process  is  practically  the  same  in  both  cases.  The 
main  characteristic  in  Stilton  cheese  is  that  it  should 
contain  a  uniform  growth  of  blue  mold  distributed 
through  its  interior  mass. 

Starting  mold-formation. — The  salt  before  being 
applied  should  be  mixed  with  a  small  amount  of 

397 


MAKING   DIFFERENT    KINDS    OF    CHEESE  399 

mold  growth.  As  a  result  of  this  even  distribu- 
tion of  salt  through  the  curd,  the  mold  becomes 
uniformly  distributed  over  the  surface  of  each  piece 
of  curd. 

Pressing  cheese. — The  cheese  is  made  in  ordinary 
Young- America  hoops  and  should  weigh  about  12 
pounds  each.  The  pressure  should  be  light  but  con- 
tinuous for  at  least  48  hours. 

Ripening  process. — To  have  Stilton  cheese  ripen 
into  the  best  condition  it  should  be  kept  in  a  damp, 
moldy  cellar,  where  the  temperature  does  not  go 
above  65°  F.  Here  the  cheese  soon  becomes  coated 
with  blue  mold,  which  influences  the  ripening 
process. 

Stilton  cheese  should  not  be  consumed  before  it  is 
at  least  2  months  old. 

ENGLISH  SAGE  CHEESE 

Early  stages  of  process. — Up  to  the  time  of  mill- 
ing, the  process  is  similar  to  that  of  cheddar  cheese. 
The  method  usually  followed  is  to  divide  the  milk, 
placing  about  one- fourth  in  a  small  vat,  to  which  is 
added  green  vegetable  coloring-matter  at  the  rate  of 
12  ounces  for  1,000  pounds  of  milk.  The  balance  of 
the  milk  is  handled  without  being  colored.  When  the 
whey  is  removed,  the  colored  curd  is  evenly  mixed 
with  the  uncolored  to  produce  the  desired  mottled  ap- 
pearance. (This  result  can  also  be  accomplished  with- 
out dividing  the  milk  by  treating  the  curd  with  the 
coloring-matter  just  before  salting.)  Before  pressing, 
sage  flavoring-extract  is  sprayed  over  the  curd.  When 


40O     SCIENCE   AND   PRACTICE  OF   CHEESE-MAKING 

finished,  the  cheese  should  present  a  uniformly  green 
mottled  appearance. 

Pressing  cheese.— The  regular-sized  English  sage 
cheese  weighs  about  5  pounds,  but  in  America  all  sizes 
are  found,  weighing  from  2  to  80  pounds.  The  pres- 
sure in  hoops  should  be  continuous  for  24  to  48  hours. 

Ripening  process. — Sage  cheese  can  be  ripened  in 
an  ordinary  cellar  or  cool  room  where  the  temperature 
does  not  go  above  60°  F.  It  should  be  held  until  it 
has  developed  the  pronounced  flavor  that  is  charac- 
teristic of  the  cheese. 

COTTAGE-CHEESE 

Cottage-cheese  is  manufactured  and  consumed 
extensively  in  the  United  States.  The  original 
Dutch  cottage-cheese  is  the  product  made  by  al- 
lowing milk  to  stand  until  it  coagulates  by  the 
ordinary  process  of  souring.  The  curd  is  put  into 
cotton  bags  to  drain,  and,  after  all  free  whey  has 
escaped,  the  curd  is  salted.  It  is  then  pressed  into 
the  form  of  balls  and  is  ready  for  immediate  con- 
sumption. 

The  modern  method  of  cottage-cheese-making 
differs  somewhat  from  the  above  and  gives  a  more 
uniform  quality  of  cheese. 

Material  to  use. — Skim-milk  should  be  used, 
as  whole-milk  loses  too  much  of  its  fat  in  the  manu- 
facturing process. 

Preparation  and  use  of  starter. — In  making  cot- 
tage-cheese on  a  large  scale,  time  can  be  saved  and 
quality  improved  by  hastening  the  souring  of  the 
milk  through  the  use  of  a  starter  prepared  in  the 


MAKING   DIFFERENT    KINDS    OF    CHEESE  40! 

manner  already  described  (p.  18).  The  character  of 
the  starter  is  of  much  importance,  since  the  flavor  of 
the  cheese  almost  entirely  depends  upon  it.  Impure 
starters  may  cause  slimy  fermentation,  and  from  such 
curd  the  whey  will  not  separate  easily. 

1.  Method    of    making    cottage-cheese    without 
starter. — Milk   is   kept   at   a   temperature   of   70°    to 
75°  F.  until  well  curdled,  which  will  usually  require 
about  48  hours.       The  curdled  mass  is  then  broken 
by  hand   or   cut   by   a   curd-knife   into   large   pieces, 
which  should  be  as  uniform  as  possible.     The  tem- 
perature  is   raised   to  90°    F.,   where  it   is   kept   till 
the    whey    appears    clear.       Heating    should    not    be 
done   too    rapidly,   as   it    injures   the   texture   of   the 
cheese.       From  30  to  40  minutes  should  be  required 
for    this.       About    15    minutes    after    completion    of 
the    heating,    or    when    the    whey    has    become    well 
separated  from  the  curd,   the  whey  is  removed  and 
the  curd  placed  in  muslin  bags  or  on  racks,  where 
it  is  allowed  to  drain. 

The  curd  is  then  salted  at  the  rate  of  I  pound  for 
100  pounds  of  curd,  or  according  to  taste,  then  shaped 
into  pound  or  half-pound  balls,  and  finally  wrapped  in 
oiled  paper.  For  the  finest  quality  of  cheese,  the  curd, 
before  being  made  into  balls,  should  be  mixed  with 
thick,  ripened  cream  at  the  rate  of  I  ounce  of  cream 
for  I  pound  of  cheese. 

2.  Method  of  making  cottage-cheese  with  use  of 
starter. — As  soon  as  the  skim-milk  is  placed  in  the 
manufacturing   vat,   from   2   to  3   per   cent   of   good 
commercial   starter  is   added  and   thoroughly    mixed 
through  the  entire  mass.     The  subsequent  steps  are 
similar  to  those  given  in  preceding  paragraph. 


4O2     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

3.  Method  of  making  cottage-cheese  with  use  of 
starter  and   rennet. — The   starter   is   added   as   pre- 
viously   described.      About    8    hours    later    rennet- 
extract   is   added   at   the    rate    of    I    ounce   for   each 
1,000  pounds  of  milk.       The  rennet  should  be  well 
diluted  with  cold  water  to  prevent  too  rapid  coagu- 
lation.    The  balance  of  the  process  is  similar  to  that 
already  described.     When  rennet  is  used,  the  coagula- 
tion can  be  secured  with  a  smaller  percentage  of  acid 
development.     About  0.4  per  cent  acid  in  the   whey 
at  the  time  of  its  removal  makes  the  best  flavor  and 
texture. 

4.  Method  of  making  cottage-cheese  from  skim- 
milk  and  buttermilk. — This  process  is  now  becoming 
popular      with      manufacturers      of      cottage-cheese, 
since   it  affords  a  way  of  utilizing  milk  that  might 
otherwise    be    wasted.       The    buttermilk    and    skim- 
milk  are  mixed  in  various   proportions.       The  tem- 
perature for  heating  the  milk  depends  on  the  amount 
of    buttermilk    and    the    amount    of    acidity.       The 
lower  the  temperature   used   consistent  with   a   good 
coagulation,    the    smoother    will    be    the    texture    of 
the  cheese.     In  making  cottage-cheese  by  any  of  these 
methods  the  quality  can  generally  be   improved  and 
greater   uniformity    secured   by    the    use   of   a   small 
amount  of  rennet. 

5.  Method  of  making  cottage-cheese  by   direct 
addition   of  hydrochloric   acid. — Have   the   milk   at 
70°  to  80°   F.     Measure  out  pure  hydrochloric  acid, 
of  specific  gravity  1.20,  at  the  rate  of  10  ounces  for 
loo    pounds    of    milk.       Dilute    with    ten    times    its 
weight   of   cold    water    and    add    to   milk   gradually, 
stirring  the  milk  constantly  while   the   acid  is  being 


MAKING   DIFFERENT    KINDS    OF    CHEESE  403 

added.  Continue  the  stirring  until  the  curd  sepa- 
rates completely,  leaving  a  clear  whey  entirely 
free  from  milkiness.  The  whey  is  then  removed  from 
the  curd  and  the  operation  completed  as  before.  In 
order  to  get  the  proper  flavor,  it  will  be  necessary  to 
mix  with  the  curd  some  sour,  thick  milk  or  cream. 
This  method  does  not  give  as  satisfactory  results  as 
the  others  described. 

Qualities  of  cottage-cheese. — Flavor  and  texture 
are  the  most  important  qualities  in  cottage-cheese. 
The  flavor  should  be  that  of  mildly-soured  milk 
or  well-ripened  cream.  There  should  be  an  entire 
absence  of  all  objectionable  flavor,  such  as  bitter 
taste,  stable  flavor,  etc.  If  the  cheese  tastes  too  sour 
it  is  usually  due  to  keeping  too  much  whey  in  the 
curd.  The  use  of  a  starter  is  apt  to  insure  the  right 
kind  of  flavor.  The  texture  of  cottage-cheese  is 
largely  dependent  on  the  amount  of  moisture  in  the 
cheese.  When  the  percentage  of  moisture  is  much 
below  70,  the  cheese  is  harsh,  dry  and  sawdust-like. 
The  right  texture  of  cottage-cheese  is  smooth  and 
free  from  grittiness.  Difficulty  is -often  experienced 
in  securing  a  uniform  quality  at  all  seasons  of  the 
year.  The  trouble  is  generally  caused  by  too  sud- 
den changes  in  the  temperature  of  the  curd  or  in 
the  development  of  lactic  acid.  Cottage-cheese 
should  be  kept  in  a  cool  place.  It  usually  sells  for 
5  to  10  cents  per  pound. 

Yield  of  cottage-cheese. — From  100  pounds  of 
milk  one  should  obtain  from  20  to  22  pounds  of  cheese. 
Variation  in  moisture  makes  much  variation  in 
yield. 


404     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

Composition  of  cottage-cheese. — Cottage-cheese 
of  the  best  texture  contains  70  to  75  per  cent  of 
moisture.  Curdling  milk  at  too  high  a  temperature 
and  heating  the  curd  too  high  or  too  long  will  make 
the  cheese  too  dry.  Cottage-cheese  contains  about 
3.5  to  4  per  cent  of  milk  sugar  and  2  to  2.5  per  cent 
of  nitrogen. 

PASTEURIZED    NEUFCHATEL   CHEESE 

This  type  of  soft  cheese  is  one  of  the  most  pal- 
atable of  the  kind.  It  is  mild  in  flavor  and  easily 
digested. 

Method  of  making. — Place  30  pounds  of  clean, 
sweet,  whole-milk  in  an  ordinary,  plain  shotgun 
can.  The  milk  should  then  be  heated  to  165°  F. 
for  20  minutes  by  placing  the  can  in  hot  water. 
After  reaching  this  temperature  it  should  be  imme- 
diately cooled  to  72°  F.  When  cool,  i.o  cubic  cen- 
timeter of  clean,  commercial  starter  is  added, 
diluted  in  100  cc.  of  cold  water.  When  the  starter 
has  been  evenly  stirred  through  the  milk,  rennet 
is  added  at  the  rate  of  0.4  cc.  to  30  pounds  of 
milk.  The  rennet  should  be  diluted  with  cold 
water,  at  the  rate  of  I  cc.  of  rennet  to  99  cc.  of 
water.  Enough  rennet  should  be  used  to  give  a 
firm  coagulation  in  12  hours.  As  soon  as  the  milk 
has  become  firmly  coagulated,  it  should  be  poured 
from  the  can  onto  a  strainer-rack  where  the  whey 
is  allowed  to  drain  from  it.  At  this  time,  .the  whey 
dripping  from  the  curd  should  have  from  0.30  to 
0.32  per  cent  acidity.  High  acidity  spoils  the  char- 
acteristic flavor  and  taste.  While  the  curd  is  dry- 
ing, it  should  have  the  portions  on  the  outside  of 


MAKING  DIFFERENT    KINDS   OF   CHEESE  405 

the  strainer  stirred  into  the  more  moist  portion  in 
the  center.  This  is  to  prevent  hard  particles  form- 
ing from  excessive  drying.  Some  pressure  may  be 
used  to  aid  in  expelling  the  whey.  The  draining  of 
whey  should  be  so  regulated  that,  at  the  time  of  salt- 
ing, it  will  not  have  more  than  0.40  per  cent  of  acidity. 
When  all  free  whey  has  escaped,  salt  is  applied  at  the 
rate  of  iy2  pounds  to  100  pounds  of  cheese.  The 
cheese  is  shaped  by  small  cylindrical  molds  and  then 
wrapped  in  parchment  paper  and  tin-foil.  After  being 
kept  for  24  hours  in  a  cool  place,  the  cheese  is  then 
ready  for  eating. 

CREAM  CHEESE 

The  manufacture  of  cream  cheese  is  very  similar 
to  that  of  pasteurized  Neufchatel  cheese,  with  the 
exception  that  the  milk  is  not  usually  pasteurized. 
Milk  is  modified  so  that  it  tests  about  10  per  cent  of 
milk-fat.  At  the  time  of  adding  rennet,  the  acidity 
should  not  be  more  than  0.15  per  cent. 

The  cheese  is  shaped  by  square  molds  and  each 
weighs  usually  about  l/4  pound. 

Sometimes  cream  cheese  is  made  by  adding  cream 
to  the  curd  of  pasteurized  Neufchatel  cheese  just 
before  salt  is  applied.  This  method  makes  a  cheese 
of  very  fine  quality. 

CLUB-CHEESE 

Club-cheese  is  one  of  the  most  extensively  used 
varieties  of  cheese.  Practically  every  hotel  and 
restaurant  in  every  country  uses  more  or  less  of  it. 


406     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

The  manufacturing  process  is  simple  enough,  and  yet 
the  desired  quality  is  hard  to  obtain.  The  value  of 
the  cheese  depends  entirely  upon  the  quality  of  the 
constituents  used. 

Method  of  making. — One  grinds  8  pounds  of 
well-ripened  cheddar  cheese  of  finest  quality  in  an 
ordinary  meat-grinding  machine.  After  the  cheese 
has  been  through  the  machine  once,  one  pound  of 
butter  of  the  best  quality  is  mixed  with  it  and  the 
whole  mass  again  run  through  the  machine.  The 
mixture  is  then  stirred  and  worked  with  the  hands 
till  free  from  all  lumps.  It  is  then  packed  in  jars 
of  some  form  and  must  be  kept  in  a  cool  place.  It 
is  well  to  smear  the  inside  walls  of  the  jar  with 
melted  butter  before  packing  the  cheese  in  it  and 
then  put  a  thin  layer  of  melted  butter  over  the  top 
of  the  packed  cheese  before  putting  on  cover. 
Finest  club-cheese  usually  sells  for  about  40  cents  a 
pound. 

EDAM  CHEESE 

Edam  cheese  is  a  sweet-curd  cheese,  made  from 
partially  skimmed  milk.  It  comes  to  the  market  in 
the  form  of  round,  red  balls,  each  weighing  from  3^2 
to  4  pounds  when  cured.  They  are  largely  manu- 
factured in  Northern  Holland  and  derive  their  name 
from  a  town  which  is  famous  as  a  market  for  this 
kind  of  cheese 

Kind  of  milk  used. — Milk  from  which  one-fourth 
to  one-third  of  the  fat  has  been  removed  is  used. 
Too  great  pains  cannot  be  taken  in  regard  to  the 
condition  of  the  milk.  It  should  be  fresh,  free  from 


MAKING   DIFFERENT    KINDS    OF    CHEESE  407 

every  trace  of  taint;  in  brief,  it  should  be  in  as  per- 
fect condition  as  it  is  possible  to  have  milk. 

Treatment  of  milk  before  adding  rennet. — The 
temperature  of  the  milk  should  be  brought  up  to  a 
point  not  below  85°  F.  nor  much  above  88°  F.  When 
the  desired  temperature  has  become  constant,  then  the 
coloring-matter  should  be  added  to  the  milk  and 
thoroughly  incorporated  by  stirring  before  the  rennet 
is  added. 

Addition  of  rennet  to  milk. — When  the  tempera- 
ture reaches  the  desired  point  85°  to  88°  F.  and 
remains  there  stationary,  the  rennet-extract  is 
added,  4^  to  5^2  ounces  being  taken  for  1,000 
pounds  of  milk,  or  enough  to  coagulate  the  milk 
in  the  desired  time,  at  the  actual  temperature  used. 
The  milk  should  be  completely  coagulated,  ready 
for  cutting,  in  about  12  to  18  minutes  from  the  time 
the  rennet  is  added.  The  same  precautions  observed 
in  making  cheddar  cheese  should  be  followed  in 
making  Edam  cheese  with  reference  to  care  in  add- 
ing the  rennet,  such  as  careful,  accurate  measurement, 
dilution  with  pure  water  before  addition  to  milk, 
etc. 

Cutting  the  curd. — When  the  curd  breaks  clean 
across  the  ringer,  it  should  be  cut;  the  curd  is  cut  a 
very  little  softer  than  in  the  cheddar  process  as 
ordinarily  practiced.  First,  a  vertical  knife  is  used 
and  the  curd  is  cut  lengthwise,  after  which  it  is 
allowed  to  stand  until  the  slices  of  curd  begin  to 
show  the  separation  of  whey.  Then  the  vertical 
knife  is  used  in  cutting  crosswise,  after  which  the 
horizontal  knife  is  at  once  used.  Any  curd  adher- 
ing to  the  bottom  and  sides  of  the  vat  is  carefully 
removed  by  the  hand,  after  which  the  curd-knife  is 


408     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

again  passed  through  the  mass  of  curd  lengthwise  and 
crosswise,  continuing  the  cutting  until  the  curd  has 
been  cut  as  uniformly  as  possible  into  very  small 
pieces. 

Treatment  of  curd  after  cutting. — When  the  cut- 
ting is  completed,  then  one  commences  at  once  to 
heat  the  curd  up  to  the  temperature  of  93°  to  96° 
F.  The  heating  is  done  as  quickly  as  possible. 
While  the  heating  is  in  progress,  the  curd  is  kept 
constantly  agitated  to  prevent  settling  and  conse- 
quent overheating.  As  soon  as  the  curd  shows 
signs  of  hardening,  which  the  experience  of  the 
worker  will  enable  him  to  determine,  the  whey  is 
drawn  off  until  the  upper  surface  of  the  curd  ap- 
pears, when  one  should  commence  to  fill  the  press- 
molds. 

Filling  molds,  pressing  and  dressing  cheese. — 
The  molds,  which  are  described  later  in  detail,  are 
well  soaked  in  warm  water  previous  to  use,  in 
order  to  prevent  too  sudden  chilling  of  curd  and 
consequent  checking  of  separation  of  whey.  As 
soon  as  the  whey  is  drawn  off,  as  indicated  above, 
one  commences  to  fill  the  pressing-molds.  The  fill- 
ing should  be  done  as  rapidly  as  possible  to  prevent 
too  great  cooling  -of  -curd.  When  the  curd  has  been 
put  into  the  molds,  its  temperature  should  not  be 
below  88°  F.  Unless  care  is  taken  to  keep  the 
curd  covered,  the  portion  that  is  last  put  into  the 
molds  may  become  too  much  cooled.  In  making 
Edam  cheese  on  a  small  scale,  it  is  a  good  plan  to 
squeeze  the  moisture  out  by  the  hands  as  much  as 
possible  and  then  break  it  up  again  before  putting 
in  the  molds,  when  the  curd  should  be  pressed 


MAKING  DIFFERENT    KINDS    OF   CHEESE  409 

into  the  mold  by  the  hands  as  firmly  as  possible. 
The  molds  should  be  filled  as  nearly  alike  as  pos- 
sible. The  cheese  should  weigh  from  5  to  5^4 
pounds  each  when  ready  for  the  press.  When  the 
filling  of  molds  is  completed,  they  are  put  under 
continual  pressure  of  20  to  25  pounds  for  about  25 
or  30  minutes.  While  the  cheese  is  being  pressed, 
some  sweet  whey  is  heated  to  a  temperature  of  125° 
or  130°  F.  and  this  whey  should  not  be  allowed  to 
go  below  120°  F.  at  any  time  while  it  is  being  used. 
When  the  cheeses  are  taken  from  their  molds,  each 
is  put  into  the  warm  whey  for  two  minutes,  then 
removed  and  dressed.  For  dressing  Edam  cheese 
the  ordinary  cheese-bandage  cloth  is  used.  This  is 
cut  into  strips  which  should  be  long  enough  to 
reach  entirely  around  the  cheese  and  overlap  an 
inch  or  so,  and  which  should  be  wide  enough  to 
cover  all  but  a  small  portion  of  the  ends  of  the 
cheese  when  put  in  place.  Before  putting  on  the 
bandage,  all  rough  projections  should  be  carefully 
pared  from  the  cheese.  In  putting  on  the  bandage, 
the  cheese  is  held  in  one  hand  and  the  bandage  is 
wrapped  carefully  around  the  cheese,  so  that  the 
whole  cheese  is  covered,  except  a  small  portion 
on  the  upper  and  lower  surface  of  the  cheese. 
These  bare  spots  are  covered  by  small  pieces  of 
bandage  cloth  of  a  size  sufficient  to  cover  the  bare 
surface.  The  bandage  is  kept  wet  with  the  warm, 
sweet  whey,  thus  facilitating  the  process  of  dress- 
ing. After  each  cheese  is  dressed,  it  should  be 
replaced  in  the  pressing-mold,  care  being  taken 
that  the  bandage  remains  in  place  and  leaves  no 
portion  of  the  surface  of  the  cheese  uncovered  and 


4IO     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

in  direct  contact  with  the  mold.  The  cheese  is  then 
put  under  continual  pressure  of  60  to  120  pounds 
and  kept  under  this  continual  pressure  for  6  to  12 
hours. 

Salting  and  curing. — There  are  two  methods 
which  may  be  employed  in  salting,  dry-salting  and 
wet-salting.  In  dry-salting,  when  the  cheese  is  finally 
taken  from  the  press,  it  is  removed  from  the  press- 
mold,  its  bandage  is  removed  completely  and  the 
cheese  placed  in  another  mold,  quite  similar,  known 
as  the  salting-mold.  Each  cheese  is  placed  in  a 
salting-mold  with  a  coating  of  fine  salt  completely 
surrounding  it.  The  cheese  is  salted  in  this  way 
once  each  day  for  5  or  6  days.  Each  day  the  cheese 
should  be  turned  when  it  is  replaced  in  the  mold, 
so  that  it  will  not  be  rounded  on  one  end  more 
than  another.  This  is  for  the  purpose  of  making 
both  ends  uniform  in  shape,  giving  each  the  proper 
rounding  peculiar  to  the  shape  of  the  cheese.  In 
the  method  of  wet-salting,  the  cheese  is  placed 
in  a  tank  of  salt  brine,  made  by  dissolving  common 
salt  in  water  in  the  proportion  of  about  one  pound 
of  salt  to  2^2  quarts  of  water.  Each  cheese  is 
turned  once  a  day  and  should  be  left  in  the  brine  7 
or  8  days.  When  the  cheese  is  taken  from  the 
salting-mold  or  salt  bath  it  is  placed  in  warm  water 
and  is  given  a  vigorous,  thorough  brushing  in  order 
to  remove  all  slimy  or  greasy  substances  that  may 
have  accumulated  on  the  outer  surface  of  the 
cheese.  When  the  surface  of  the  cheese  is  well 
cleansed,  it  is  carefully  wiped  dry  with  a  linen 
towel  and  placed  upon  a  shelf  in  the  curing-room. 
In  being  placed  on  the  shelves,  the  cheeses  should 


MAKING  DIFFERENT    KINDS    OF   CHEESE  41 1 

be  placed  in  contact  so  as  to  support  one  another, 
until  they  have  flattened  out  at  both  ends  so  much 
that  they  can  stand  upright  alone.  Then  they  are 
placed  far  enough  apart  to  allow  a  little  air  space 
between  them.  Another  method  of  securing  the 
flattened  ends  is  to  support  each  cheese  on  opposite 
sides  by  wedge-shaped  pieces  of  wood.  After  they 
are  placed  on  the  shelves  in  the  curing-room,  they 
are  turned  once  a  day  and  rubbed  with  the  bare 
hand  during  the  first  month,  twice  a  week  during 
the  second  month,  and  once  a  week  after  that. 
When  any  slimy  substance  appears  on  the  surface 
of  the  cheese,  it  should  be  washed  off  at  once  with 
warm  water  or  sweet  whey.  The  special  conditions 
of  the  curing-room  will  be  noticed  in  detail  below. 
When  the  cheeses  are  about  two  months  old,  they 
can  be  prepared  for  market,  which  is  done  in  the 
following  manner:  They  are  first  made  smooth  on 
the  surface  by  being  turned  in  a  lathe  or  in  some 
other  manner,  after  which  the  surface  is  colored. 
For  coloring,  some  carmine  is  dissolved  in  alcohol 
or  ammonia  to  get  the  proper  shade,  and  in  this 
color-bath  the  cheeses  are  placed  for  about  one  min- 
ute, when  they  are  removed  and«  allowed  to  drain, 
and  as  soon  as  they  are  dry  the  outside  of  each 
cheese  is  rubbed  with  boiled  linseed  oil,  in  order  to 
prevent  checking.  They  are  then  wrapped  in  tin- 
foil, which  is  done  very  much  like  the  bandaging. 
Care  must  be  taken  to  put  the  tin-foil  on  so  that  it 
presents  a  smooth,  neat  appearance.  The  cheeses 
are  finally  packed  in  boxes,  each  box  containing  12 
cheeses,  arranged  in  two  layers  of  six  each,  with  a 
separate  partition  for  each  cheese. 


412     SCIENCE   AND    PRACTICE    OF    CHEESE-MAKING 

Curing-room. — Much  more  attention  must  be 
given  to  the  conditions  of  the  curing-room  as  re- 
gards moisture  and  temperature  than  in  the  case  of 
cheddar  cheese.  The  curing-room  should  be  well 
ventilated,  should  be  quite  moist  and  its  tempera- 
ture should  be  kept  between  50°  and  65°  F.  These 
conditions  are  best  secured  in  some  form  of 
.cellar. 

Utensils  employed  in  making  Edam  cheese. — 
Aside  from  the  molds,  continual  press  and  salt- 
ing-vat, the  same  apparatus  that  is  used  in  making 


FIG.   50 — EDAM    PRESS-MOLD   AND    COVER 

cheddar  cheese  can  be  used  in  making  Edam  cheese. 
The  pressing-mold  is  turned  preferably  from  .white 
wood  or,  in  any  ca*se,  from  wood  that  will  not  taint. 
Each  mold  consists  of  two  parts;  the  lower  part 
constitutes  the  main  part  of  the  mold,  the  upper 
portion  is  simply  a  cover.  The  lower  portion  or 
body  of  the  mold  has  several  holes  in  the  bottom, 
from  which  the  whey  flows  when  the  cheese  is 
pressed.  Care  must  be  taken  to  prevent  these  holes 
being  stopped  up  by  curd.  This  portion  of  the 
mold  is  about  6  inches  deep  and  6  inches  in  diam- 
eter across  the  top.  The  salting-mold  has  no  cover 


MAKING   DIFFERENT    KINDS    OF    CHEESE 


413 


and  the  bottom  is  provided  with  only  one  hole  for 
the  outflow  of  whey;  in  other  respects  it  is  much 
like  the  pressing-mold. 

Fig.  50  shows  the  external  appearance  of  the 
press-mold  with  cover  in  position,  the  inner  surface 
of  the  cover,  and  the  inside  appearance  of  the  press- 
mold.  Fig.  51  shows  the  press-mold  and  cover  in 


FIG.  51 — CROSS-SEC- 
TION   OF    EDAM 
PRESS-MOLD   AND 
COVER 


FIG.  52 — EDAM  SALT- 
ING-MOLD IN  CROSS- 
SECTION 


cross-section.  Fig.  53  shows  the  salting-mold  in 
external  and  internal  appearance  and  Fig.  52  shows 
cross-section  of  the  same. 

Qualities  of  Edam  cheese. — The  flavor  of  a  per- 
fect Edam  cheese  is  difficult  to  describe.  It  is  mild, 
clean  and  pleasantly  saline.  In  imperfect  Edams  the 
flavor  is  more  or  less  sour  and  offensive. 

In  body,  a  perfect  Edam  cheese  is  solid,  rather  dry 
and  mealy  or  crumbly.  This  condition  is  secured 
by  the  use  of  partially  skimmed  milk,  together  with 
the  special  conditions  of  manufacture  employed. 


414     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

In  texture,  the  perfect  Edam  cheese  should  be  close 
and  free  from  pores. 

Some  general  remarks. — There  are  a  few  points 
which  may  be  best  brought  to  our  attention  by  con- 
trasting some  of  the  conditions  used  in  the  manufac- 
ture of  Edam  cheese  with  those  employed  in  the 
manufacture  of  our  American  cheddar  cheese. 

(i)  One  is  made  from  partially  skimmed  milk; 
the  other,  when  at  its  best,  is  made  from  whole 
mi.lk. 


FIG.    53 — SALTING-MOLD,    INSIDE    AND 
OUTSIDE    APPEARANCE 

(2)  While  it  is  very  important  in  making  cheddar 
cheese  to  have  the  milk  in  perfect  condition,  it  is  abso- 
lutely essential  in  making  Edam  cheese. 

(3)  In   making  cheddar   cheese,   the   removal  of 
moisture  is  largely  effected  in  the  vat  by  the  use  of 
a  higher  temperature  in  heating  the  curd.     In  mak- 
ing Edam  cheese,  the  removal  of  moisture  depends 
more  upon  the  fineness  of  cutting  the  curd  and  sub- 
sequent  pressing.     The  latter   process   is   much   less 
economical  as  regards  loss  of  milk  constituents. 

(4)  In    making    cheddar    cheese,    more    or    less 
lactic    acid    is    formed    according    to    special    condi- 
tions;    in  making  Edam  cheese,  every  effort  is  made 


MAKING   DIFFERENT    KINDS    OF    CHEESE  415 

to  hasten  the  process  at  every  stage  and  prevent  the 
formation  of  lactic  acid.  In  one  case,  we  work  to 
produce  an  acid  curd;  in  the  other,  a  curd  as  free  as 
possible  from  acid. 

(5)  The  details    of    salting    and    curing    differ 
radically    in    the    two    methods.        In    general,    the 
manufacture  of  Edam  cheese  requires  labor  and  care 
in   giving  attention  to   many  more   details   than   the 
manufacture   of   cheddar  cheese,   however   much   the 
latter  should  have  for  best  success. 

(6)  Edam  cheese  sells  for  two  or  three  times  as 
much  per  pound  as  the  best  American  cheddar. 

GOUDA  CHEESE 

Gouda  cheese  is  a  sweet-curd  cheese  made  from 
whole-milk.  In  shape,  the  Gouda  cheese  is  somewhat 
like  a  cheddar  with  the  sharp  edges  rounded  off  and 
sloping  toward  the  outer  circumference  at  the  middle 
from  the  end  faces.  They  usually  weigh  10  or  12 
pounds  each,  though  they  vary  in  weight  from  8  to 
1 6  pounds.  They  are  largely  manufactured  in  southern 
Holland,  and  derive  their  name  from  the  town  of  the 
same  name. 

Kind  of  milk  used. — Fresh,  sweet  milk  that  has 
been  produced  and  cared  for  in  the  best  possible 
manner. 

Temperature  of  milk  before  adding  rennet. — The 
temperature  of  the  milk  should  be  brought  up  to  a 
point  not  below  88°  F.  nor  much  above  90°  F.  When 
the  desired  temperature  has  been  reached  and  has 
become  constant,  then  the  coloring-matter  is  added 
and  thoroughly  incorporated  by  stirring  before  the 
rennet  is  added. 


4l6    SCIENCE   AND    PRACTICE    OF    CHEESE-MAKING 

Addition  of  rennet  to  milk. — The  rennet  should 
not  be  added  until  the  milk  has  reached  the  desired 
temperature  (88°  to  90°  F.)  and  this  temperature  has 
become  constant.  Then  one  adds  4  to  5  ounces  of 
fresh  rennet-extract  for  1,000  pounds  of  milk.  The 
milk  should  be  completely  coagulated,  ready  for 
cutting,  in  15  or  20  minutes.  The  same  precautions 
should  be  used  in  adding  rennet  as  those  previously 
mentioned  in  connection  with  the  manufacture  of 
Edam  cheese. 

Cutting  the  curd. — The  curd  should  be  cut  when 
it  is  of  about  the  hardness  generally  observed  for 
cutting  in  the  cheddar  process.  The  cutting  is  done 
exactly  as  in  the  cheddar  process  except  that  the 
curd  is  cut  a  little  finer  in  the  Gouda  cheese.  Curd 
should  be  about  the  size  of  peas  or  wheat  kernels 
when  ready  for  press  and  as  uniform  in  size  as 
possible. 

Treatment  of  curd  after  cutting. — When  the  cut- 
ting is  completed,  one  commences  at  once  to  heat 
the  curd  and  to  stir  carefully.  The  heating  and 
constant  stirring  are  continued  until  the  curd 
reaches  a  temperature  of  104°  F.,  which  should 
require  from  30  to  40  minutes.  When  the  curd  be- 
comes rubber-like  in  feeling  and  makes  a  squeak- 
ing sound  when  chewed,  the  whey  should  be  run 
off.  The  whey  should  be  entirely  sweet  when  it  is 
removed. 

Pressing  and  dressing  cheese. — After  the  whey 
is  run  off,  the  curd  is  put  in  the  molds  at  once 
without  salting.  Pains  should  be  taken  in  this  proc- 
ess to  keep  the  temperature  of  the  curd  as  near 
100°  F.  as  possible.  Each  cheese  is  placed  under 


MAKING   DIFFERENT    KINDS    OF    CHEESE  417 

continual  pressure  amounting  to  10  or  20  times  its 
own  weight  and  kept  for  about  half  an  hour.  The 
first  bandage  is  put  on  in  very  much  the  same  man- 
ner as  the  bandage  in  Edam  cheese-making.  The 
cheese  is  then  put  in  press  again  for  about  one  hour. 
The  first  bandage  is  then  taken  off  and  a  second  one 
like  the  first  one  put  on  with  great  care,  taking  pains 
to  make  the  bandage  smooth,  capping  the  ends  as 
before.  The  cheese  is  then  put  in  press  again  and 
left  12  hours  or  more. 

Salting  and  curing. — When  the  cheese  is  taken 
from  the  press  the  bandage  is  removed  and  it  is 
placed  for  24  hours  in  a  curing-room  like  that  used 
in  curing  Edam  cheese,  as  previously  described  (p. 
412).  Each  cheese  is  then  rubbed  all  over  with  dry 
salt  until  the  salt  begins  to  dissolve,  and  this  same 
treatment  is  continued  twice  a  day  for  ten  days. 
At  the  end  of  that  time,  each  cheese  is  carefully 
and  thoroughly  washed  in  warm  water  and  dried 
with  a  clean  linen  towel.  The  cheeses  are  then 
placed  on  the  shelves  of  the  curing-room,  turned 
once  a  day  and  rubbed  like  cheddars.  The  tempera- 
ture and  moisture  are  controlled  as  described  in  the 
curing  process  of  Edam  cheese.  If  the  outer  surface 
of  the  cheese  gets  slimy  at  any  time,  they  are  care- 
fully washed  in  warm  water  and  dried  with  clean 
towels.  Under  these  conditions,  the  cheese  ripens  in 
2  or  3  months. 

Utensils  employed  in  making  Gouda  cheese. — 
The  molds,  continual  press  and  curing-room  are 
the  only  things  needed  in  the  making  of  Gouda 
cheese  that  differ  from  the  utensils  employed  in 
making  cheddar  cheese.  The  mold  used  for  Gouda 


41 8     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

cheese  consists  of  two  parts,  which  are  shown 
separate  in  Fig.  54,  while  in  Fig.  55  the  two  parts 
are  shown  united,  ready  for  pressing.  These  molds 
were  made  of  heavy  pressed  tin.  The  inside  diam- 
eter at  the  middle  is  about  10  inches.  The  diameter 
of  the  ends  is  about  6l/2  inches.  The  height  of  the 
mold  (as  seen  in  Fig.  55)  is  about  $y2  inches,  and 
this  represents  the  thickness  of  the  cheese,  but  by 
pushing  the  upper  down  into  the  lower  portion,  the 


A  B 

FIG.       54 TWO       PARTS       OF 

GOUDA      MOLD,      SHOWN 
SEPARATE 


FIG.       55 — TWO       PARTS       OF 
GOUDA    MOLD,    UNITED 


thickness  can  be  decreased  as  desired.  A  simple 
way  to  make  a  Gouda  mold  is  to  take  two  rounded 
wash  basins  made  of  pressed  tin,  cut  them  down 
so  that  they  will  be  about  il/2  inches  deep.  Then 
on  one  portion  is  soldered  a  rim  of  tin  about  3 
inches  wide  (see  Fig.  54  A,  or  Fig.  55,  lower  por- 
tion of  mold).  On  the  second  wash  basin  is  sol- 
dered another  rim  of  tin  3  inches  wide,  about  y2 
inch  of  which  projects  beyond  the  open  side  of 
the  wash  basin,  the  rest  projecting  on  the  other 
side  (see  Fig.  54  B  and  Fig.  55,  upper  portion). 
This  upper  part,  or  B,  should  be  made  of  such 
diameter  that  it  will  just  fit  into  the  inside  of  the 


MAKING    DIFFERENT    KINDS    OF    CHEESE  419 

other  portion,  as  shown  in  Fig.  55.  The  upper  por- 
tion is  provided  with  two  rings  soldered  on  and  the 
lower  portion  with  two  handles  to  facilitate  handling. 
In  the  ends  of  the  molds  or  the  portions  made  from 
wash  basins  -there  are  18  or  20  perforations  about  l/% 
inch  in  diameter,  made  for  the  purpose  of  letting  the 
whey  run  out. 


PartV 

Methods  of  Testing 
Cheese-Factory  Organization 
Literature  of  Cheese-Making 


burette 


ho/det 


COCK 
cor* 


p/ncfi 
icocfc 


CUj 


PUBLOW'S    APPARATUS    FOR    MEASURING    ACIDITY 


CHAPTER  XXVIII 

Methods  of  Testing  Used  in  Cheese-Making 

It  is  our  purpose  in  this  chapter  to  give,  for  the 
most  part,  only  an  outline  of  the  methods  of  testing* 
used  in  connection  with  cheese-making,  since  the  full 
details  would  occupy  too  much  space.  The  methods 
to  be  considered  cover  the  following  substances: 

1.  Fat  in  (i)  milk,  (2)  whey,  (3)  curd,  and  (4) 
cheese. 

2.  Acidity  in  (i)  milk,  (2)  whey,  (3)  curd,  and 
(4)  cheese. 

3.  Strength  of  rennet-extracts. 

4.  Dirt  and  ferments  in  milk. 

5.  Specific  gravity. 

6.  Hot-iron  test. 

7.  Casein  in  milk. 

THE  BABCOCK  TEST  FOR  FAT 

This  is  a  method  for  determining  the  amount  of 
fat  in  milk  and  its  products.  The  test  is  based  ( I )  on 
the  action  of  strong  sulphuric  acid  upon  the  solids 
of  milk  other  than  fat,  by  which  the  milk-fat  is 
released  from  the  restraining  influence  of  other  com- 
pounds and  so  is  free  to  collect  in  one  separate  mass, 
and  (2)  on  the  use  of  centrifugal  force,  which  is  em- 
ployed to  complete  separation  of  the  fat.  The  Bab- 

*For  a  full  description  of  all  the  details  of  most  of  these  methods,  see 
"Modern  Methods  of  Testing  Milk  and  Milk  Products,"  published  by  the 
Orange  Judd  Company. 


424     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

cock  test  finds  occasion  for  use  in  connection  with 
cheese-making  in  the  following  ways :  ( i )  Testing 
milk  of  individual  patrons  when  dividends  are  made 
on  the  basis  of  the  milk- fat;  (2)  testing  milk  to 
ascertain  if  its  fat  content  has  been  seriously  affected 
by  skimming;  (3)  testing  milk  to  use  as  a  basis  for 
estimating  the  yield  of  cheese  and  regulating  the 
amount  of  salt  used  (p.  38)  ;  (4)  testing  whey 
and  press-drippings  to  ascertain  if  the  loss  of  fat 
is  excessive,  and  (5)  testing  cheese  for  percentage 
of  fat. 

Apparatus  and  materials  used. — The  following  list 
includes  the  apparatus  and  materials  used  in  making 
this  test:  (i)  Test-bottles,  graduated  from  o  to  10 
per  cent,  so  that  each  smallest  division  represents  0.20 
per  cent  when  17.5  cubic  centimeters  (18  grams)  of 
milk  are  used;  (2)  pipette  for  measuring  milk,  hold- 
ing 17.6  cubic  centimeters  to  mark;  (3)  measure 
for  acid,  holding  17.5  cubic  centimeters  to  mark; 
(4)  centrifugal  machine,  having  a  wheel  12  to  20 
inches  in  diameter,  easily  capable  of  being  run  at  a 
speed  of  700  to  1,200  revolutions  a  minute;  and  (5) 
commercial  sulphuric  acid  having  a  specific  gravity 
between  1.82  and  1.83,  preferably  just  1.825  (Test- 
ing Milk,  etc.,  pp.  32-52). 

Sampling  milk  for  testing. — Milk  that  has  curdled, 
or  on  the  surface  of  which  cream  has  risen  and  dried, 
or  milk  the  fat  of  which  has  partially  churned,  is1  dif- 
ficult to  sample.  These  difficulties  should  not  be  com- 
mon in  cheese-factory  work,  but,  when  they  arise, 
careful  attention  should  be  given  to  the  details  pre- 
scribed for  such  cases  (Testing  Milk,  etc.,  pp.  22- 
24).  The  samples  to  be  tested  must  be  thoroughly 
mixed. 


TESTS   USED   IN   CHEESE-MAKING  425 

Composite  samples. — In  order  to  avoid  testing 
milk  daily,  composite  samples  may  be  prepared  and 
tested  at  intervals  of  a  week  or  ten  days.  Much  care 
must  be  used  in  preparing  and  keeping  composite 
samples  (Testing  Milk,  etc.,  pp.  24-31). 

Method  of  operating  the  test. — (Testing  Milk 
etc.,  pp.  53-66).  In  brief  outline,  the  different 
steps  are  given  as  follows: 

(1)  Mix  thoroughly  sample  of  milk,  which  is  at 
60°  to  70°  F. 

(2)  Quickly  fill  pipette  to  mark  with  milk. 

(3)  Run  milk  into  test-bottle. 

(4)  Fill  acid-measure  to  mark  with  acid  and  pour 
into  test-bottle. 

(5)  (a)   Mix  milk  and  acid  thoroughly  by  rotary 
motion;    (b)  let  stand  2  to  5  minutes;    and  (c)  mix 
again. 

(6)  Put    test-bottles    in    tester    (centrifuge)    and 
whirl  4  or  5  minutes  at  proper  speed. 

(7)  (a)    Add  fairly  hot  water  up  to  neck  of  bot- 
tles;   (b)   whirl  one  minute;    (c)   add  hot  water  to 
8  or  9  per  cent  mark;   and  (d)  whirl  one  minute. 

(8)  Read  results  at  temperature  of  about  130°  F. 
Special    precautions. — The    following    statements 

give  an  outline  of  the  particular  points  to  be  observed 
in  making  the  test  in  order  to  insure  accuracy: 

(1)  Always  make  tests  in  duplicate. 

(2)  Make  sure  that  the  sample  is  a  representative 
one. 

(3)  Have  the  temperature  of  the  milk  and  acid  at 
60°  to  70°  F.  before  putting  in  test-bottle. 

(4)  Use  only  acid  of  right  strength. 


426     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

(5)  Mix  milk  and  acid  thoroughly  as  soon  as  acid 
is  added. 

(6)  Mix  a  second  time  after  a  short  interval. 

(7)  Make  sure  that  the  tester  runs  at  the  right 
speed  and  does  not  jar. 

(8)  Use  only  clean,  soft  water  in  filling  bottles. 

(9)  Read   bottles   before   they  cool   and  at  about 
130°  F. 

( 10)  To   guard   against   mistakes,   read   each  test 
twice. 

Testing  whey  for  fat.— The  test  is  conducted  in 
the  usual  way,  except  that  special  bottles  having  small 
necks  for  more  accurate  reading  are  used  and  less  acid 
is  generally  sufficient  (Testing  Milk,  etc.,  pp.  81- 
83). 

Testing  curd  and  cheese. — Care  must  be  taken  in 
sampling.  The  weighed  sample  (8  to  10  grams)  is 
treated  in  the  test-bottle  with  about  10  cc.  of  wate'r 
(65°-7O°  F.),  after  which  the  acid  (17.6  cc.)  is  added 
and  the  test  completed  in  the  usual  way  (Testing  Milk, 
etc.,  pp.  83-85).  The  acid  should  be  added  carefully, 
about  i  cc.  at  a  time,  mixing  the  acid  and  water  by 
shaking  after  each  addition.  After  all  the  acid  has 
been  thus  added,  shake  the  whole  vigorously  until  the 
cheese  is  completely  disintegrated. 

TEST  FOR  ACIDITY 

Fresh  milk  contains  substances  (casein  and  acid 
phosphates)  which  neutralize  alkali  and  in  this  respect 
behave  like  acids.  The  amount  of  this  acidity  is  ap- 
proximately equivalent  to  o.io  per  cent.  Amounts  of 
acid  above  this  figure  are  usually  due  to  the  action  of 
lactic  acid  that  has  been  formed  bv  the  bacterial  decom- 


TESTS    USED    IN    CHEESE-MAKING  427 

position  of  the  sugar  in  the  milk.  It  is  the  amount  of 
acid  thus  formed  which  we  usually  desire  to  determine. 

The  method  of  ascertaining  the  acidity  of  milk  is 
based  upon  the  chemical  action  taking  place  between 
acids  and  alkalis.  Acids  and  alkalis  neutralize  each 
other  and  form  compounds  called  salts,  which  are 
neutral  (neither  acid  nor  alkaline).  A  substance  used 
in  showing  whether  a  solution  is  acid,  alkaline  or 
neutral  is  called  an  indicator.  The  one  in  most  com- 
mon use  is  a  compound  called  phenolphthalein,  which 
turns  pink  in  alkali  solutions  and  colorless  in  acid  or 
neutral  solutions.  Only  a  few  drops  need  be  used  in 
making  one  test.  There  are  several  different  methods 
for  testing  acidity,  but  all  are  alike  in  principle. 

Publow's  acid  test. — (i)  The  apparatus  (p.  422) 
consists  of  (i)  a  plain  5-pint  bottle  with  an  opening 
in  the  bottom,  through  which  a  brass  pipe  is  connected 
so  securely  as  to  prevent  leakage.  (2)  A  small  2-ounce 
wash-bottle,  fastened  to  the  neck  of  the  large  bottle 
by  a  copper  band  and  connected  by  means  of  rubber 
corks  and  glass  tubing.  (3)  A  plain  10  cc.  burette 
graduated  in  tenths  and  a  simple  wire  burette-holder. 
(4)  A  straight,  non-bulbous,  Q-gram  pipette,  which 
can  be  easily  cleaned.  (5)  A  simple  rubber-stoppered 
dropping-bottle.  (6)  A  plain  white  cup  and  stirring- 
rod.  (7)  A  small  bottle  containing  50  cc.  of  a  solu- 
tion of  caustic  soda  (equal  to  9.2  grams  of  purest 
caustic  soda),  which,  when  added  to  2,250  cc.  of  water, 
makes  2,300  cc.  of  a  tenth-normal  alkali  solution.  The 
large  bottle  is  marked  to  show  the  level  of  2,300  cc.  in 
order  to  save  time  in  measuring.  (8)  A  small  bottle 
of  phenolphthalein  indicator. 

(2)  Preparing  alkali  solution. — As  the  most  ac- 
curate, convenient  and  economical  method  of  prepar- 


428     SCIENCE   AND  PRACTICE   OF   CHEESE-MAKING 

ing  a  tenth-normal  alkali  solution,  a  concentrated  solu- 
tion of  caustic  soda  is  advised,  of  which  50  cc.  is  suffi- 
cient to  make  2,300  cc.  of  a  tenth-normal  solution.  This 
solution  retains  its  strength  indefinitely  when  tightly 
corked.  The  tenth-normal  solution  is  prepared  by 
adding  the  contents  of  the  small  bottle  of  alkali  to  the 
large  bottle  without  any  loss,  rinsing  the  small  bottle 
several  times  and  each  time  pouring  the  rinsings  into 
the  large  bottle.  Soft  water  is  then  added  to  the  large 
bottle  until  it  reaches  the  level  of  the  mark  (2,300  cc.) 
filed  on  the  bottle.  In  order  to  keep  this  alkali  solution 
without  loss  of  strength,  the  small  wash-bottle  referred 
to  above  (2)  is  attached  to  the  neck  of  the  larger  one 
in  the  manner  indicated,  after  being  half  filled  with  the 
tenth-normal  alkali  solution. 

(3)  Method  of  use. — The  liquid  to  be  tested  (milk, 
whey,  cream  or  starter)  is  measured  by  means  of  the 
9-gram  pipette  and  run  into  the  white  cup.  Two  drops 
of  phenolphthalein  solution  are  added,  after  which  the 
alkali,  a  drop  at  a  time,  is  run  into  the  cup  from  the 
burette  (arranged  in  the  manner  indicated  on  p.  422), 
until  the  solution  in  the  cup,  which  must  be  constantly 
stirred,  shows  a  very  faint  pink  color  that  does  not 
disappear  for  15  seconds  or  longer.  Each  tenth  cc.  of 
alkali  used  represents  .01  per  cent  of  acid. 

Manns'  acid  test. — For  details  see  Testing  Milk, 
etc.,  pp.  101-103. 

Farrington's  alkaline  tablet  test. — In  this  form  of 
test,  the  alkali  and  indicator  are  mixed  together  in  the 
form  of  tablets.  Five  tablets  are  dissolved  so  as  to 
make  97  cubic  centimeters  of  solution,  which  is  added, 
in  small  portions,  from  a  graduated  cylinder  to  17.5 
cubic  centimeters  of  milk  until  the  pink  color  re- 
mains. Each  cubic  centimeter  of  alkali  solution 


TESTS    USED    IN    CHEESE-MAKING  429 

used  stands  for  o.oi  per  cent  of  acidity  equivalent  to 
lactic  test  (Testing  Milk,  etc.,  pp.  103-105). 

Testing  acidity  of  whey. — Whey  is  tested  in  the 
same  manner  as  milk.  The  sample  of  whey  tested 
should  be  free  from  all  curd  particles,  since  curd  has 
some  power  to  neutralize  alkali  (Testing  Milk,  etc., 
pp.  109-110). 

Testing  acidity  of  cheese. — An  extract  of  a 
weighed  amount  of  cheese  is  made  and  this  extract 
is  tested  for  acidity  in  the  usual  way  (Testing  Milk, 
etc.,  p.  no). 

Special  precautions  in  making  acidity  tests. — 
In  carrying  out  tests  for  acidity,  certain  points  of  the 
operation  must  be  kept  carefully  in  mind. 

1 I )  The  material  tested  must  be  thoroughly  mixed 
before  taking  a  sample. 

(2)  The  water  used  in  preparing  the  alkali  solu- 
tion should  be  neutral,  soft  and  clean.     Distilled  water 
is  best. 

(3)  Alkaline  tablets  must  be  kept  dry. 

(4)  The  alkali  solution,  whichever  form  is  used, 
must  .be  kept  from  contact  with  air  as  much  as  pos- 
sible to  prevent  change  of  strength. 

(5)  Prepare  fresh  solution  of  alkaline  tablets  for 
best  results. 

(6)  Make  tests  only  in  a  good  light. 

QUICK  TEST  FOR  ACIDITY  OF  MILK 

It  is  often  desirable  to  ascertain  quickly  whether 
milk  or  cream  contains  more  or  less  than  0.2  or  0.3 
per  cent  of  acid.  This  can  be  done  by  the  following 
method :  An  alkali  solution  is  prepared  by  dissolving 
in  an  8-ounce  bottle  2  alkali  tablets  for  each  ounce 


43°      SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

of  water  used.  A  No.  10  brass  cartridge  shell,  on 
which  a  wire  handle  is  soldered,  is  used  for  meas- 
uring the  sample  to  be  tested  and  also  the  alkali.  A 
cartridgeful  of  milk  is  placed  in  a  teacup  and  then 
a  cartridgeful  of  the  alkali  solution  is  added.  The 
contents  of  the  cup  are  mixed  by  a  rotary  motion. 
If  the  sample  tested  remains  white,  it  contains  over 
0.2  per  cent  of  acidity ;  if  a  pink  color  remains,  the 
acidity  is  less  than  0.2  per  cent.  The  intensity  of  the 
pink  color  indicates  the  relative  amount  of  acid  pres- 
ent, since  the  color  will  be  more  intense  in  proportion 
as  there  is  less  acid.  Any  other  measure  may  be  used 
in  place  of  the  brass  cartridge-shell,  but  in  every  case 
care  must  be  taken  to  use  equal  amounts  of  milk  and 
of  alkali  solution. 

This  test  can  be  used  at  the  weigh-can  in  case  of 
milks  that  are  suspected  of  containing  0.2  per  cent  or 
more  of  acid. 

THE  MARSCHALL  TEST 

In  this  test  the  same  general  procedure  is  followed 
as  in  the  Monrad  test,  but  the  rate  of  coagulation  is 
observed  in  a  different  way.  The  following  pieces 
of  apparatus  are  used:  (a)  A  testing  cup  or  basin, 
of  about  a  pint  capacity,  for  holding  the  milk  to 
be  tested.  On  the  inside  wall  of  this  cup  there  are 
graduated  spaces  beginning  with  zero  at  the  top  and 
going  by  half-divisions  to  7  near  the  bottom  of  the 
cup,  while  in  the  bottom  of  the  cup  is  a  glass  tube 
with  a  very  small  bore,  (b)  An  ounce  bottle  with  a 
mark  on  it  to  indicate  20  cc.  (c)  A  spatula  for  stir- 
ring the  milk,  (d)  A  i  cc.  pipette. 


TESTS    USED    IN    CHEESE-MAKING  431 

The  operation  of  conducting  this  test  is  as  follows : 
Measure  with  the  pipette  i  cc.  of  the  rennet-extract 
used  and  empty  it  into  the  ounce  bottle,  previously 
half  filled  with  clean,  cold  water.  Rinse  the  pipette 
two  or  three  times  by  drawing  water  into  it  from  the 
bottle  and  allowing  it  to  run  back  into  the  bottle.  Mix 
well  by  shaking.  Then  place  the  milk  to  be  tested 
in  the  test-cup,  setting  it  in  a  level  position  and  allow- 
ing the  milk  to  run  out  at  the  bottom.  Taking  the  bot- 
tle of  diluted  rennet  in  one  hand  and  the  spatula  in 
the  other,  watch  the  level  of  the  milk  in  the  cup.  The 
moment  the  upper  surface  of  the  milk  drops  to  the 
zero  mark,  pour  the  diluted  rennet  into  the  milk  and 
stir  well.  Then  leave  it  alone.  When  the  milk  coagu- 
lates, it  stops  running  through  the  glass  tube.  From 
the  graduated  scale,  read  the  number  of  spaces  un- 
covered on  the  inside  of  the  cup,  showing  how  many 
divisions  of  milk  have  run  out.  The  more  slowly  the 
milk  coagulates,  the  larger  the  amount  that  runs  out; 
the  more  quickly  the  milk  coagulates,  the  smaller  the 
amount  that  runs  out  and  the  fewer  spaces  there  are 
uncovered.  When  about  2^2  spaces  are  uncovered, 
the  milk  is  ready  for  addition  of  rennet.  The  tempera- 
ture must  be  watched,  being  tested  at  the  start  and 
finish,  especially  in  a  cold  room. 

Some  objectionable  features  of  the  Marschall  test 
should  be  noticed.  A  difference  in  the  size  of  the  bore 
of  the  glass  tube  in  the  bottom  of  the  cup  obviously 
makes  a  difference  in  the  results.  It  is  found  that  the 
size  of  the  bore  of  the  glass  tubing  varies  in  different 
cups.  Therefore,  the  results  given  by  one  cup  can  not 
be  compared  with  those  of  another,  unless  they  are 
tested  on  the  same  milk  and  found  to  agree.  Special 


43^      SCIENCE   AND    PRACTICE    OF    CHEESE-MAKING 

pains  must  be  taken  to  keep  the  tube  open,  since  a  lit- 
tle dirt  quickly  stops  it.  The  Marschall  test  is  con- 
venient for  ordinary  work,  but  is  not  capable  of  as 
great  delicacy  as  is  the  Monrad  test.  Results  obtained 
by  different  workers  can  be  compared  by  the  Monrad 
test,  but  not  by  the  Marschall  test 

THE  MONRAD  TEST 

This  test  is  based  upon  the  amount  of  time  required 
for  a  definite  quantity  of  milk  at  a  given  temperature 
to  become  coagulated  by  a  fixed  quantity  of  rennet. 

The  pieces  of  apparatus  required  are  the  following: 
( i )  A  tin  cylinder  for  measuring  milk,  holding,  when 
full,  1 60  cc.,  (2)  a  5  cc.  pipette,  (3)  a  50  cc.  glass 
flask,  (4)  a  thermometer,  and  (5)  a  half-pint  tin  basin. 

In  testing  the  ripeness  of  milk  by  means  of  rennet- 
extract,  one  first  prepares  a  dilute  solution  of  the 
rennet,  as  follows:  One  measures  with  the  small  pi- 
pette 5  cc.  of  rennet-extract  into  the  50  cc.  flask.  The 
pipette  is  then  rinsed  twice  with  water  by  sucking  it 
full  of  cold,  clean  water  to  the  mark,  the  rinsings  also 
being  run  into  the  50  cc.  flask.  The  flask  is  then  filled 
with  water  to  the  50  cc.  mark,  and  the  contents  are 
well  mixed  by  shaking.  The  next  step  is  to  fill  the 
tin  cylinder  with  the  well-mixed  milk  to  be  tested  and 
this  is  emptied  into  the  half-pint  basin.  The  milk 
must  be  at  the  temperature  at  which  one  adds  the 
rennet  in  cheese-making,  which  is  generally  about 
84°  to  86°  F.  To  the  milk  at  the  desired  tempera- 
ture, one  adds  5  cc.  of  the  diluted  rennet  solution, 
mixes  it  through  the  milk  quickly,  using  the  ther- 
mometer as  a  stirrer.  The  exact  time  when  the 


TESTS    USED    IN    CHEESE-MAKING  4^3 

rennet-extract  is  added  to  the  milk  is  noted  by  the 
second  hand  of  a  watch,  and  then  again  when  the 
milk  has  coagulated;  the  number  of  seconds  re- 
quired to  coagulate  the  milk  is  recorded.  The 
exact  point  of  coagulation  can  be  seen  more 
sharply  by  scattering  a  few  particles  of  charcoal 
(as  the  blackened  end  of  a  partly  burned  match) 
on  the  surface  of  the  milk,  and  then  with  the  ther- 
mometer starting  the  surface  into  motion  around  the 
dish.  The  black  particles  stop  the  instant  the  milk 
coagulates.  By  using  a  stop-watch  great  accuracy 
and  delicacy  can  be  attained.  Care  should  be  taken 
to  keep  the  temperature  of  the  milk  at  the  one  desired 
point,  testing  frequently  with  the  thermometer;  and 
in  case  the  temperature  drops,  it  can  be  raised  by 
placing  the  basin  of  milk  in  warm  water.  In  ordinary 
cheddar  cheese-making,  milk  is  ready  for  the  addition 
of  rennet  when  it  coagulates  in  30  to  60  seconds  under 
the  foregoing  conditions. 

METHOD  OF  TESTING  RENNET-EXTRACTS 

Different  brands  of  rennet-extract  vary  somewhat 
in  their  strength ,  that  is,  the  rapidity  and  completeness 
with  which  they  coagulate  milk  when  used  in  the  same 
amount.  It  is  therefore  important  to  have  a  means  of 
testing  their  strength,  in  order  that  their  value  may 
be  definitely  known  and  that  cheese-makers  may  be 
able  to  know  in  advance  of  using  how  much  they  must 
use  for  the  best  results.  The  Monrad  and  Marschall 
tests  are  available  for  this  purpose. 

In  order  to  test  the  comparative  strength  of  differ- 
ent rennet-extracts,  one  treats  different  portions  of 
the  same  milk  with  the  different  extracts  to  be  tested. 


434      SCIENCE   AND    PRACTICE   OF    CHEESE-MAKING 

In  all  other  respects,  the  details  of  the  methods  pre- 
viously given  are  followed.  All  conditions  must  be 
kept  alike  in  the  different  tests.  The  strength  of  the 
rennet-extracts  is  shown  by  the  rapidity  with  which 
the  milk  is  coagulated;  the  stronger  the  rennet,  the 
less  the  time  of  coagulation. 

METHOD  OF  TESTING  PEPSIN 

Pepsin  is  beginning  to  be  used  in  cheese-making  as 
a  substitute  for  rennet-extract.  Vivian  has  worked 
out  the  important  details.  The  scale-pepsin,  of  strength 
known  as  1-3000,  prepared  from  stomachs  of  sheep, 
is  recommended.  It  may  be  used  at  the  rate  of  5 
grams  for  1,000  pounds  of  milk.  In  testing  scale- 
pepsin  by  the  rennet-test,  one  can  dissolve  the  scale- 
pepsin  at  the  rate  of  5  grams  in  4  ounces  of  water 
and  use  this  solution  exactly  like  a  rennet-extract  with 
milk.  It  should  be  tested  in  comparison  with  a  sam- 
ple of  rennet-extract  whose  use  in  cheese-making  has 
been  tested,  the  test  being  made  on  different  portions 
of  the  same  milk. 

TESTS  FOR  FERMENTS   AND  INSOLUBLE 
DIRT  IN  MILK 

Those  forms  of  micro-organisms  or  ferments  that 
make  trouble  in  cheese-making  are  not  readily  per- 
ceptible to  the  senses  when  milk  is  delivered  at  the 
cheese-factory,  but  the  results  of  their  work  develop 
later  either  during  the  cheese-making  process  or  later 
in  ripening  cheese.  When  such  ferments  appear, 
it  is  desirable  to  locate  them  in  some  particular  herd 
or  herds  with  a  view  to  removal  of  the  causes  of 


TESTS    USED    IN    CHEESE-MAKING  435 

trouble.  It  is  also  desirable  to  get  an  idea  of  the 
amount  of  suspended  dirt  in  milk,  as  this  may  often 
be  an  indication  of  the  general  bacterial  condition  of 
the  milk,  since  bacteria  generally  keep  company  with 
dirt.  We  have  tests  for  accomplishing  these  objects. 

TEST  FOR  DIRT  IN  MILK 

The  following  is  a  quick,  simple,  practicable  method 
for  indicating  in  a  rough  way  how  much  suspended 
dirt  milk  contains:  Provide  several  granite-iron  fun- 
nels 2^/2  or  3  inches  in  diameter.  Place  in  these  some 
clean  absorbent  cotton,  making  the  upper  surface  as 
smooth  and  flat  as  practicable  and  somewhat  compact. 
Have  these  near  the  weighing-can  so  that  one  can  be 
attached  on  inside  of  can.  When  milk  is  dumped  in 
can  and  thoroughly  mixed,  take  a  pint  and  pour  on 
cotton  in  funnel.  Any  suspended  dirt  quickly  shows. 
The  method  might  be  improved  by  laying  a  circular 
piece  of  white  muslin  on  top  of  the  cotton.  The  test 
performed  under  the  eyes  of  a  patron  would  be  con- 
vincing. Milk  should  contain  no  visible  dirt  in  sus- 
pension. 

THE  FERMENTATION  OR  WISCONSIN 
CURD-TEST 

Milk  frequently  contains  objectionable  forms  of 
organisms  or  ferments  that  are  not  made  perceptible 
by  ordinary  methods  of  observation.  The  condition 
arises  particularly  in  milk  used  for  cheese-making  and 
may  result  in  serious  injury  to  the  quality  of  the 
cheese.  The  Wisconsin  experiment  station  (Wisconsin 
experiment  station  I2th  and  I5th  annual  reports, 
1895  and  1898)  has  applied  certain  principles  to  the 


43^      SCIENCE   AND    PRACTICE   OF    CHEESE-MAKING 

development  of  a  test  that  enables  one  to  identify  milk- 
containing  certain  forms  of  undesirable  ferments  likely 
to  do  serious  injury.  This  method  is  based,  in  gen- 
eral, upon  the  plan  of  making  conditions  favorable  for 
the  rapid  development  of  the  ferments  present  in  milk. 

Apparatus. — The  apparatus  consists  of  the  follow- 
ing parts :  ( I )  Pint  glass  jars  or  tin  cans  with  covers, 
(2)  a  well-insulated  tank  to  hold  the  jars,  (3)  rennet- 
extract,  (4)  a  thermometer,  (5)  a  case-knife  or  sim- 
ilar instrument  for  cutting  curd,  and  (6)  a  small 
pipette  for  measuring  rennet-extract. 

Operation  of  test. — The  test  is  conducted  as  fol- 
lows: The  jars,  including  covers,  just  previous  to 
use,  are  sterilized  with  live  steam,  scalding  water  or 
dry  heat  (212°  F.).  Each  jar  or  can  is  filled  about 
two-thirds  full  with  the  milk  to  be  tested  and  the  ster- 
ilized cover  put  on  at  once.  The  jars  are  then  placed 
in  the  tank  which  is  filled  with  water  at  100°  to  102° 
F.  up  to  the  upper  surface  of  the  milk  in  the  jars.  The 
temperature  of  the  water  should  be  kept  at  100°  to 
102°  F.  during  the  whole  operation.  To  hasten  the 
warming  of  the  milk,  the  jars  are  taken  out  and  shaken 
occasionally.  The  temperature  of  the  milk  is  observed 
with  a  sterile  thermometer,  and  when  the  milk  has 
reached  98°  F.,  one  adds  10  drops  of  rennet-extract 
to  each  jar  and  mixes  thoroughly  by  giving  the  con- 
tents of  the  jar  a  rotary  motion.  When  the  milk  has 
coagulated,  it  is  allowed  to  stand  until  it  is  firm,  usu- 
ally about  20  minutes.  To  enable  the  whey  to  sepa- 
rate more  readily,  the  curd  is  then  cut  fine  with  a 
thin  knife,  which  must  be  carefully  rinsed  with  hot 
water  after  finishing  each  jar  and  before  using  it  in 
another,  in  order  to  avoid  carrying  contamination  from 


TESTS    USED    IN    CHEESE-MAKING  437 

one  milk  to  another  and  spoiling  the  test.  The  curd 
is  allowed  to  settle  completely.  When  the  whey  has 
been  separating  half  an  kour,  the  samples  are  exam- 
ined for  flavor  by  smelling,  after  which  the  whey 
is  carefully  poured  out  of  the  jars  and  this  is  repeated 
at  intervals  of  30  to  40  minutes  for  8  hours  or  more. 
Under  the  favorable  conditions  of  temperature,  similar 
to  those  employed  in  cheese-making,  the  organisms 
present  develop  readily  and  reveal  their  presence  in 
different  characteristic  ways.  The  jars  are  finally 
opened,  any  whey  present  is  drained  off,  and  the  fol- 
lowing tests  are  applied :  ( i )  The  curd  is  cut  into  two 
pieces.  The  curd  will  be  solid  and  free  from  holes 
on  the  cut  surfaces,  if  the  milk  is  not  tainted.  If  it 
is  spongy  and  full  of  holes,  it  contains  those  undesir- 
able organisms  that  produce  gases  in  the  curd  and  in- 
jure it  for  cheese-making,  showing  in  the  form  of 
"floating  curds"  and  "huffy"  cheese.  The  holes  are 
usually  small,  their  common  name  being  "pin-holes." 
(2)  The  curd  is  examined  with  reference  to  any 
marked  disagreeable  odors  that  may  be  present.  Some 
undesirable  organisms  reveal  their  presence  by  smell 
without  making  spongy  curd.  This  may,  perhaps,  be 
best  perceived  by  smelling  of  a  freshly  cut  surface 
of  the  curd.  Offensive  odors  are,  of  course,  an  unde- 
sirable indication.  Special  apparatus  for  perform- 
ing the  test  is  furnished  by  dairy-supply  houses,  but 
pint  fruit- jars  and  other  home-made  appliances  will 
answer  satisfactorily. 

By  this  method  one  can  learn  what  particular  lot 
of  milk  among  several  is  responsible  for  undesirable 
fermentations.  Moreover,  having  traced  the  source  of 
contamination  to  a  single  herd  of  cows,  it  is  easily 


SCIENCE   AND    PRACTICE   OF    CHEESE-MAKING 


possible,  by  applying  the  test  to  single  cows,  to  ascer- 
tain which  individual  or  individuals  may  be  the  source 
of  trouble.  . 

Precautions.  —  Two  points  must  be  carefully  ob- 
served in  carrying  out  this  test:  (i)  The  tempera- 
ture must  be  kept  as  near  98°  F.  as  possible,  in 
order  that  the  bacteria  may  develop  as  desired. 
This  can  be  done  by  keeping  the  temperature  of  the 
water  surrounding  the  jars  at  100°  to  102°  F.  The 
temperature  must  be  watched.  (2)  The  thermometer 
and  the  knife  used  should  be  made  not  only  clean  but 
sterile  each  time  after  using  in  one  sample  before 
placing  them  in  another. 

TEST  FOR  SPECIFIC  GRAVITY  AND 
SOLIDS  OF  MILK 

f  Milk  Testing,  etc.,  pp.  127-132) 

Process    of    using    Quevenne    lactometer.  —  The 

sample  of  milk  to  be  tested  for  specific  gravity  is 
brought  to  a  temperature  between  50°  and  70°  F.  For 
convenience  the  milk  is  placed  in  a  cylinder,  which 
is  nearly  filled.  The  lactometer  is  carefully  lowered 
into  the  milk  until  it  floats  and  is  allowed  to  re- 
main half  a  minute  or  more.  Then  one  reads  and 
records  (i)  the  point  at  which  the  lactometer  scale 
comes  in  contact  with  the  upper  surface  of  the  milk; 
and  (2)  the  temperature.  The  lactometer  reading  is 
then  corrected,  if  the  temperature  is  above  or  below 
60°  F.  For  example,  the  lactometer  settles  in  milk, 
which  is  at  a  temperature  of  65°  F.,  to  the  point 
marked  29.  Adding  to  the  reading  for  correction  o.i 
for  each  degree  above  60°  F.,  which  in  this  case  is  0.5, 


TESTS    USED    IN    CHEESE-MAKING  439 

the  reading  becomes  29.5.  This  means  that  the  spe- 
cific gravity  is  1.0295.  If  the  temperature  of  the 
milk  were  55°  F.,  the  correction  is  subtracted  and 
the  reading  becomes  28.5,  equal  to  specific  gravity 
1.0285. 

Babcock's  formulas  for  solids  and  solids-not-fat. — 
The  following  formulas  were  devised  by  Dr.  Bab- 
cock: 

(1)  Formula  for  determining  solids-not-fat. — Sol- 
ids-not-fat=*4L-|-o.2f,  in  which  L  is  the  reading  of 
the  Quevenne  lactometer  and  f  is  the  per  cent  of  fat 
in  the  milk. 

(2)  Formula   for   determining   solids   in   milk. — 
Total  solids=j4L+i.2f. 

These  formulas  can  be  expressed  in  the  form  of 
rules  as  follows: 

Rule  i. — To  find  the  per  cent  of  solids-not-fat  in 
milk,  divide  the  reading  of  the  Quevenne  lactometer 
by  4,  and  to  the  result  add  the  number  giving  the  per 
cent  of  fat  in  the  milk  multiplied  by  0.2. 

Rule  2. — To  find  the  per  cent  of  solids  in  milk,  di- 
vide the  Quevenne  lactometer  reading  by  4,  and  to 
the  result  add  the  number  giving  the  per  cent  of  fat 
multiplied  by  1.2. 

THE  HOT-IRON  TEST 

This  test  is  used  for  the  purpose  of  ascertaining 
when  to  remove  whey  from  curd  and  when  to  mill 
curd.  An  iron  of  convenient  size  and  length  for  hold- 
ing, as  a  half-inch  gas-pipe,  is  heated  fairly  hot  at  one 
end.  The  iron  is  carefully  wiped  with  a  cloth  until 
it  is  clean  and  smooth.  A  handful  of  curd  is  then 
taken  and  placed  in  dry  cloth  and  squeezed  by  the 


440     SCIENCE  AND   PRACTICE  OF   CHEESE-MAKING 

hand,  until  the  surface  has  been  well  dried.  The  curd 
is  then  gently  pressed  against  the  portion  of  the  iron 
where  it  is  hot  enough  to  make  the  curd  stick  to 
the  iron  but  not  hot  enough  to  scorch  it.  The  curd  is 
then  carefully  drawn  away  from  the  iron  and,  if  in 
proper  condition,  produces  fine,  silky  threads,  the 
length  of  which  depends  upon  the  amount  of  acidity 
of  the  curd. 


VOLUMETRIC  TEST  FOR  CASEIN 

A  new  test  for  casein  has  been  recently  worked  out 
at  the  New  York  experiment  station  by  Van  Slyke  and 
Bosworth  (Technical  Bulletin  No.  10,  Sept.,  1909).  In 
outline  the  method  is  as  follows :  Into  a  200  cc.  flask 
one  measures  17.5  cc.  (18  grams)  of  milk,  adds  about 
80  cc.  of  water  and  I  cc.  of  phenolphthalein,  after  which 
a  solution  of  sodium  hydroxid  (caustic  soda)  is  added 
until  the  mixture  is  neutral.  Standardized  acetic  acid 
is  then  added  until  the  casein  is  completely  precip- 
itated, the  volume  of  the  mixture  is  made  up  to  200  cc. 
by  addition  of  water  and  then  filtered.  Into  100  cc. 
of  the  clear  filtrate,  a  standardized  solution  of  sodium 
hydroxid  is  run  until  neutral.  The  solutions  are  so 
standardized  that  I  cc.  is  equivalent  to  i  per  cent  of 
casein  in  the  milk  examined.  Therefore,  the  number 
of  cc.  of  standard  acid  used,  divided  by  2,  less  the 
amount  of  standard  alkali  used  in  the  final  titration 
gives  the  percentage  of  casein  in  the  milk.  The  opera- 
tion usually  requires  12  to  15  minutes  when  apparatus 
and  solutions  are  at  hand  in  convenient  form  ready  for 
use;  several  determinations  can  be  carried  on  at  the 
same  time  with  much  relative  economy  of  time. 


TESTS   USED   IN    CHEESE-MAKING  44! 

Apparatus. — (i)  Two  50  cc.  burettes,  accurately 
graduated  to  one-twentieth  cc.  Automatic  burette 
fillers  save  much  time  in  making  many  determinations. 

(2)  Flasks,  so-called  volumetric,  holding  200  cc. 
and  accurately  marked.    Flasks  having  necks  4^2  to  5 
inches  long  and  ^-inch  inside  diameter  are  desirable 
for  greatest  convenience. 

(3)  Pipette  (Babcock  test  form),  accurately  grad- 
uated to  deliver  17.5  cc.  (18  grams)  of  milk. 

(4)  Pipette  graduated  to  deliver  100  cc. 

(5)  Pipette  graduated  to  deliver  about  I  cc.  and 
provided  with  a  rubber  bulb  (so-called  dropper). 

(6)  Cups,  plain  white,  holding  200  cc.  or  more. 

(7)  Funnels,   glass  or  granite-ironware,   3    to    4 
inches  in  diameter. 

(8)  Filter-papers  cut  round,  6  to  7  inches  in  diam- 
eter ;  or  fine  linen  filters  cut  to  proper  size  and  shape, 
which  can  be  washed  after  use  and  used  repeatedly. 

(9)  Measuring-cylinders,  accurately  graduated  and 
holding  1,000  cc. 

Solutions. —  (i)  Sodium  hydroxid  (caustic  soda). 
This  solution  may  be  made  most  conveniently  by  pre- 
paring a  regular  tenth-normal  solution  in  the  manner 
recommended  by  Publow  (p.  427),  and  then  diluting 
795  cc.  of  this  to  one  liter  (or  one  may  directly  dilute 
the  50  cc.  of  concentrated  alkali  to  2,900  cc.).  In 
such  a  solution  I  cc.  corresponds  to  0.09  gram  of  casein 
(or  i  per  cent).  In  making  standard  solutions,  pure 
distilled  water  should  be  used  if  possible,  or  else  as 
pure  rain-water  as  can  be  obtained.  Alkali  solutions 
must  be  kept  in  tightly-stoppered  bottles  to  prevent 
loss  of  strength.  "Alkaline  tablets"  cannot  be  used 
for  the  casein  test. 


442     SCIENCE  AND   PRACTICE   OF   CHEESE-MAKING 

(2)  Acetic  acid. — This  solution  is  so  made  that  a 
given  amount  of  it  will  exactly  neutralize  the  same 
amount  of  the  standard  alkali  solution  of  the  strength 
above  indicated.     The  simplest  way  of  preparing  this 
solution  is  to  purchase  a  normal  solution  and  dilute 
loo  cc.  of  this  to  1,260  cc.    To  prevent  fermentation  of 
dilute  acetic  acid  and  consequent  change  of  strength  on 
long  standing,  it  is  desirable  to  add  a  small  amount  of 
pure  mercuric  chlorid   (corrosive  sublimate)    and    to 
keep  the  solution  in  tightly-stoppered  bottles. 

(3)  Phenolphthalein  solution. — This    is    made  by 
dissolving  one  gram  of  the  dry,  powdered  compound  in 
100  cc.  of  50  per  cent  alcohol  and  adding  to  the  pre- 
pared solution  one  or  more  drops  of  dilute  alkali  until 
the  solution  is  very  slightly  pinkish  in  color. 

Performing  the  test. — (i)  Measuring  and  diluting 
sample  of  milk.  The  milk  to  be  tested  is  well  mixed 
and  a  17.6  cc.  pipette  filled  to  the  mark  and  the  milk 
run  into  a  200  cc.  flask.  Then  add  about  80  cc.  of 
pure,  soft  water  (preferably,  distilled). 

(2)  Neutralizing  the  milk. — Add  I  cc.  of  phenol- 
phthalein  solution  to  the  dilute  milk  and  then  run  into  it 
the  alkali  solution  from  a  burette,  in  small  portions, 
shaking  vigorously  after  each  addition  of  alkali,  until 
a  faintly,  but  distinctly,  pinkish  shade  of  color  remains 
even  after  considerable  agitation.  Marked  excess  of 
alkali  must  be  avoided. 

(a)  Preparation  of  a  color-standard. — More  satis- 
factory results  in  neutralizing  can  be  obtained  by  pre- 
paring a  color-standard  for  comparison.  This  can  be 
prepared  as  follows:  About  20  cc.  of  fresh  skim-milk 
and  80  cc.  of  water  are  put  into  a  200  cc.  flask  and  a 
very  small  amount  of  pure  corrosive  sublimate  added 
to  prevent  souring.  A  few  drops  of  ordinary  carmine 


TESTS   USED   IN    CHEESE-MAKING  443 

ink  are  considerably  diluted  with  water  and  this  vis 
carefully  added,  a  few  drops  at  a  time,  to  the  diluted 
skim-milk  until  a  faint  but  distinct  pinkish  coloration 
appears.  This  can  be  more  readily  perceived  by  plac- 
ing beside  the  flask  another  flask  half  full  of  uncolored 
diluted  skim-milk.  The  coloration  must  be  as  slight 
as  possible  and  yet  be  appreciably  distinct  when  com- 
pared with  uncolored  milk.  After  the  color-standard 
has  been  prepared,  the  flask  is  stoppered.  It  is  well  to 
keep  this  standard  in  a  dark  place  when  not  in  use. 
With  some  carmine  colors,  the  pinkish  shade  in  the 
milk  deepens  on  standing,  especially  when  exposed  to 
light,  and  with  others  it  may  fade.  If  any  deepening 
of  color  is  observed  at  any  time,  addition  of  dilute 
skim-milk  will  reproduce  the  proper  shade ;  in  case  of 
fading,  the  addition  of  one  or  more  drops  of  carmine 
ink  is  called  for.  Skim-milk  is  used  because,  in  case 
of  normal  milk,  the  fat  separates  on  standing,  adheres 
to  the  sides  of  the  flask,  and  obscures  the  color. 

(b)  Use  of  color-standard. — In  neutralizing  a 
sample  of  milk,  the  color-standard  is  placed  beside  the 
sample  under  examination  for  constant  comparison 
after  each  addition  of  alkali.  The  flasks  should  be 
placed  on  a  white  surface  and  in  a  good  light.  In  fresh 
milks,  it  is  usually  found  that  3  or  4  cc.  of  alkali  is 
sufficient  to  neutralize  the  milk.  One  can  add  2  or  3 
cc.  of  alkali  at  the  start  and  then  add  it  in  smaller  por- 
tions, until  the  milk  begins  to  show  signs  of  neutrality, 
after  which  the  alkali  is  added  drop  by  drop. 

(3)  Precipitation  of  casein. — (a)  Addition  of  acid. 
Into  the  neutralized  sample  of  diluted  milk,  which 
should  be  at  a  temperature  of  65°  to  75°  F.,  one  now 
runs  from  a. burette  some  of  the  standardized  acetic 
acid,  adding  the  acid  approximately  in  5  cc.  portions 


444      SCIENCE  AND    PRACTICE   OF   CHEESE-MAKING 

and  shaking  vigorously  for  a  few  seconds  after  each 
addition.  It  is  usually  safe  to  add  about  25  cc.  of  acid 
before  examining  the  milk  to  see  if  the  casein-separates 
in  the  form  of  white  flakes.  After  adding  20  to  25 
cc.  and  shaking,  the  mixture  is  allowed  to  stand  still. 
If  enough  acid  has  been  added,  the  casein  separates 
promptly  in  large,  white  flakes,  and  on  standing  a 
short  time  the  liquid  above  the  settled  casein  appears 
clear  and  not  atNall  milky.  If  the  addition  of  25  cc. 
of  acid  is  insufficient,  add  I  cc.  more  of  acid  and  shake ; 
continue  the  addition  of  acid  I  cc.  at  a  time,  until  the 
casein  is  observed  to  separate  promptly  and  completely 
on  standing  at  rest  for  a  short  time.  The  number  of 
cc.  of  acid  used  to  effect  precipitation  is  noted  and  this 
result  is  recorded  as  A. 

(b)  Influence  of  temperature. — For  convenience  of 
work  and  uniformity  of  results,  the  temperature  of  the 
mixture  at  the  time  of  the  addition  of  acid  may  be  be- 
tween 65°  and  75°  F.  Under  these  conditions,  many 
milks  give  satisfactory  results  with  just  30  cc.  of  acid. 
In  case  of  milks  containing  3.5  to  4  per  cent  of  casein, 
one  may  need  to  use  as  much  as  35  to  40  cc.  of  acid. 
Rarely  has  it  been  found  that  25  cc.  of  acid  is  ex- 
cessive. The  amount  of  acid  may  be  2  or  3  cc.  in  ex- 
cess of  that  required  to  effect  complete  precipitation 
without  seriously  affecting  the  accuracy  of  the  results, 
provided  the  temperature  of  the  mixture  is  below 
75°  F.  At  temperatures  above  75°  F.,  good  results  are 
attainable,  but  care  must  be  taken  not  to  use  much 
excess  of  acid;  and,  of  course,  the  higher  the  temper- 
ature, the  less  will  be  the  amount  of  acid  required.  In 
working  at  temperatures  under  65°  F.,  the  casein  sepa- 
rates more  slowly  or  requires  more  acid  to  separate 
promptly.  When  working  with  milk  that  is  much 


TESTS    USED   IN    CHEESE-MAKING  445 

below  65°  F.,  it  is  well  to  use  for  dilution  water  that 
is  at  a  temperature  of  about  80°  F. 

(4)  Filtration  of  casein. — After  the  casein  is  com- 
pletely precipitated,  one  adds  pure,  soft  (preferably, 
distilled)  water  to  the  flask  until  the  200  cc.  mark  is 
reached.  The  flask  is  then  vigorously  shaken  10  or  15 
seconds,  in  order  to  distribute  the  acid  through  the 
mixture  as  uniformly  as  possible.  The  contents  of  the 
flask  are  then  poured  on  a  clean,  dry  filter,  and  the 
filtrate  caught  in  a  cup.  The  funnels,  filter  and  cups 
used  to  catch  filtrate  should  all  be  dry  before  being 
used.  It  is  well,  generally,  to  allow  the  filtration  to 
continue  until  practically  all  of  the  liquid  has  run  into 
the  cup. 

(a)  Rapidity  of  filtration. — The  usual  time  of  filtra- 
tion should  not  exceed  3  to  5  minutes.     The  rapidity 
depends  upon  the  temperature  of  precipitation  and  the 
completeness  of  the  separation  of  casein.     In  general, 
the  higher  the  temperature  of  the  mixture  when  pre- 
cipitated with  acid,  the  more  rapid  should  be  filtration, 
other  conditions  being  uniform.    In  case  of  insufficient 
acid,  the  filtration  is  slower. 

(b)  Appearance   of   filtrate. — The   filtrate   should 
be  quite  clear,  though  this  is  not  always  a  sure  indica- 
tion that  the  right  amount  of  acid    has    been    used. 
Sometimes  the  filtrate  may  be  clear  when  not  quite 
enough  acid  has  been  used,  in  which  case  the  filtration 
is  apt  to  be  slow.    In  case  of  milk  rich  in  fat,  a  slight 
turbidity  may  appear,  due  to  fat-globules  in  the  filtrate. 
The  filtrate  should  be  free  from  all  marked  signs  of 
turbidity  or  anything  like  milkiness.    If  such  a  filtrate 
appears,  a  new  sample  of  milk  should  be  taken  and 
the  operation  repeated  from  the  beginning,  more  acid 
being  used   than   before.     With   a   little   experience, 


446     SCIENCE   AND   PRACTICE   OF   CHEESE-MAKING 

especially  under  proper  instruction,  no  difficulty  should 
be  found  in  recognizing  quickly  when  the  casein  is 
separated  so  as  to  give  satisfactory  results. 

(5)  Titration  with  alkali. — After  filtration  is  com- 
pleted, one  measures  100  cc.  of  the  filtrate  with  the 
pipette  into  a  cup  and  then  runs  into  this  from  the 
burette  the  standard  alkali  until  a  faint  but  distinct 
pink    color    remains    clearly    marked    throughout   the 
solution  for  half  a  minute  or  longer  before  beginning 
to  fade.    The  number  of  cc.  of  alkali  used  is  noted  and 
this  result  is  recorded  as  B. 

The  last  portions  of  the  alkali  must  be  added  care- 
fully, a  drop  at  a  time,  agitating  the  mixture  well  after 
each  addition.  The  exact  neutral  point  is  not  perfectly 
sharp  on  account  of  the  presence  of  phosphates,  and 
the  appearance  of  the  desired  coloration  is,  therefore, 
not  as  sudden  and  pronounced  as  might  be  desired. 
With  experience  one  should  have  no  difficulty  in  get- 
ting within  one  drop  of  the  correct  amount  of  alkali. 
The  chief  precaution  to  be  observed  is  to  have  the  same 
shade  and  duration  of  color  every  time.  Thus,  one 
should  not  in  one  titration  add  alkali  until  a  deep  pink 
coloration  appears,  lasting  for  some  minutes,  and  in 
another  a  coloration  that  disappears  within  5  seconds. 
In  the  case  of  milk  rich  in  phosphates,  the  solution 
usually  grows  quite  turbid  as  the  neutral  point  is  ap- 
proached, making  it  necessary  to  use  more  care  in  ob- 
serving the  color  of  the  end-point  of  the  reaction. 

If  one  desires  to  make  a  second  titration  of  the  same 
filtrate,  one  can  use  50  cc.  of  the  remaining  portion, 
multiplying  the  result  by  2  and  recording  this  as  B. 

(6)  Calculation  of  results. — The  calculation  of  the 
percentage  of  casein   from    (i)    the  amount  of  acid 
used  (A)  in  precipitating  casein  and  (2)  the  amount 


TESTS    USED    IN    CHEESE-MAKING  447 

of  alkali  used  (B)  in  neutralizing  100  cc.  of  filtrate 
is  very  simple.  Divide  A  by  2  and  from  the  result  sub- 
tract B;  or,  expressed  as  a  formula, 

^ 

— B=per  cent  of  casein  in  milk. 

Example:  One  used  30  cc.  (A)  of  acid  in  precip- 
itating casein  and  11.95  cc-  (B)  of  alkali  in  neutraliz- 
ing 100  cc.  of  filtrate  (one-half  of  filtrate  from  the 
casein  precipitate  corresponding  to  9  grams  of  milk). 
Substituting  30  for  A  and  11.95  f°r  B  in  the  formula, 
we  have 

^—11.95    (  =  15— ii.95)=3-<>5    (the  percentage    of 

casein  in  milk). 

(7)  Use  of  preservatives. — In  making  a  casein  de- 
termination by  this  method,  it  is  desirable,  when  possi- 
ble, to  use  milk  not  more  than  24  hours  old,  which  has 
been  kept  in  a  cool  place.  Milk  which  is  sour  or  which 
coagulates  on  heating  cannot  be  used  with  satisfac- 
tory results.  However,  by  adding  to  fresh  milk  pure, 
powdered  mercuric  chlorid  (corrosive  sublimate)  in 
the  approximate  proportion  of  I  part  to  1,000  or  1,500 
parts  of  milk,  and  then  keeping  mixture  at  a  tempera- 
ture of  50°  or  lower,  one  can  obtain  satisfactory  re- 
sults with  milk  that  has  been  kept  two  or  three  weeks. 
Milk  thus  treated  should  be  shaken  often  enough  to 
keep  the  fat  well  incorporated  in  the  body  of  the  milk. 
The  desired  amount  of  mercuric  chlorid  may  be  ap- 
proximately measured  by  taking  for  one  quart  of  milk 
the  amount  of  mercuric  chlorid  that  will  lie  easily  on 
the  surface  of  a  silver  dime,  or,  more  conveniently, 
the  amount  held  by  a  o.22-inch  pistol  cartridge-shell, 
one-half  inch  long,  when  loosely  filled.  Commercial 


SCIENCE   AND    PRACTICE   OF    CHEESE-MAKING 

mercuric    chlorid    tablets    containing    coloring-matter 
cannot  be  used. 

(8)  Summary  of  precautions. — Assuming  that  the 
graduated  glassware  is  accurate  and  the  standardized 
solutions  of,  correct  strength,  the  following  special 
points  are  to  be  observed  with  care  in  making  test. 

(a)  Preliminary    neutralization. — In     neutral-zing 
the  sample  of  milk,  excess  of  alkali  must  be  avoided, 
which  can  be  controlled  by  the  use  of  a  properly  pre- 
pared color-standard. 

(b)  Conditions    of    precipitation. — Before    precip- 
itating with  acid,  have  the  dilute,  neutralized  milk  at 
a  temperature  between  65°  and  75°  F.     Add  enough 
acid  to  cause  the  casein  to  separate  promptly  in  large 
flakes,  leaving  the  supernatant  liquid  clear.    Shake  the 
mixture  vigorously   at   intervals   during  the   addition 
of  acid ;  also  after  complete  precipitation  and  again 
after  dilution  to  200  cc.  mark. 

(c)  Filtration. — Allow  most  of  the  liquid  to  run 
through  the  filter  before  making  the  final  titration  with 
alkali. 

(d)  Titration  with  alkali. — In  titrating  the  filtrate 
with  alkali,  avoid  an  excess  of  alkali.    Add  the  alkali 
solution  cautiously  until,  after  thorough  agitation,  a 
faint  but  distinct  pink  color  remains  through  the  solu- 
tion half  a  minute  or  longer.    The  same  uniform  shade 
and  duration  of  pink  color  should  be  obtained  as  nearly 
as  possible  in  all  cases. 

(e)  Acid  milk. — Milk  that  is  sour  or  that  coag- 
ulates on  heating  should  not  be  used. 

(f)  Use   of   preservatives. — Milk    treated,     when 
fresh,  with  a  small  amount  of  pure  powdered  mercuric 
chlorid  (corrosive  sublimate)  and  then  kept  in  a  cool 
place  gives  good  results  for  two  or  three  weeks. 


TESTS    USED    IN    CHEESE-MAKING  449 

CENTRIFUGAL  TEST  FOR  CASEIN 

The  following  centrifugal  method  has  been  worked 
out  at  the  Wisconsin  station  by  Hart: 

Apparatus  and  reagents. — (i)  Testing-tube,  with 
neck  so  graduated  that  each  division  represents  0.20 
per  cent  when  one  uses  5  cc.  of  milk.  (2)  Centrifuge, 
of  special  form,  run  by  hand,  having  a  wheel  15  inches 
in  diameter  and  geared  to  give  a  speed  of  2,000  revo- 
lutions a  minute.  (3)  Pipette  for  measuring  5  cc.  of 
milk.  (4)  Cylinder  for  measuring  2  cc.  of  chloroform. 
(5)  Dilute  acetic  acid  containing  0.25  per  cent  of 
acetic  acid,  prepared  by  diluting  10  cc.  of  glacial  acetic 
acid  (99.5  per  cent)  to  100  cc.  with  water,  and  then 
diluting  25  cc.  of  this  solution  to  one  liter.  (6)  Chloro- 
form of  the  best  quality. 

Method  of  operating  test. — In  a  testing-tube  one 
puts  2  cc.  of  chloroform,  then  on  top  of  this  20  cc. 
of  the  dilute  (0.25  per  cent)  acetic  acid.  One  then 
runs  in  5  cc.  of  milk  (65°  to  75°  F.),  after  which  the 
thumb  is  placed  over  the  opening  of  the  tube  and  the 
tube  inverted  to  bring  the  mixture  into  the  barrel- 
shaped  portion  of  the  tube;  then  the  whole  is  shaken 
with  a  fair  degree  of  vigor  for  15  or  20  seconds,  ac- 
curately timed  with  watch  before  one.  In  the  shaking 
process,  the  chloroform  takes  up  most  of  the  fat  and 
the  acid  precipitates  the  casein  in  fine  particles.  The 
sample  is  then  ready  for  the  centrifuge  and  should  be 
whirled  within  30  minutes.  The  centrifuge  is  closed 
before  whirling  and  is  brought  to  a  speed  of  2,000 
revolutions  a  minute,  after  which  it  is  run  at  this  rate 
7j^  to  8  minutes.  This  must  be  done  with  such  pre- 
cision that  it  is  important  to  use  a  metronome  during 
the  operation.  After  whirling,  the  testing-tubes  are 


450      SCIENCE    AND    PRACTICE   OF    CHEESE-MAKING 

removed  and  placed  in  a  rack  in  an  upright  position 
and  then  read  after  10  minutes  or  more.  The  chloro- 
form and  fat  should  be  at  the  bottom  and  on  top  of 
this  a  white,  cylindrical  mass  of  casein.  The  end 
surfaces  of  this  casein  cylinder,  which  should  be  flat, 
are  read  on  the  scale  directly,  the  result  being  the 
per  cent  of  casein  in  the  milk,  if  the  test  is  successful. 
While  fresh  milk  is  desirable  for  best  results,  it  is  said 
that  seven-day  composite  samples  may  be  used  by 
taking  one-ounce  samples  of  milk  each  day  in  a  brown 
or  amber-colored  glass  receptacle,  adding  on  the  first 
day  and  again  on  the  third  day  one-fourth  of  an  or- 
dinary potassium  bichromate  tablet  (equal  to  il/2  or 
2  grains).  The  mixture  is  gently  agitated  daily  by  a 
rotary  motion,  and  kept  well  stoppered  in  a  dark,  cool 
place. 

Conditions  affecting  accuracy  of  results. — (i)  Use 
of  sour  milk.  (2)  Use  of  milk  containing  preserva- 
tives, except  bichromate.  (3)  Too  strong  or  too  dilute 
solution  of  acetic  acid.  (4)  Poor  quality  of  chloro- 
form. (5)  Temperature  of  acid  and  milk  below  65° 
or  above  75°  F.  (6)  Shaking  mixture  of  acid,  chloro- 
form and  milk  too  short  or  too  long  a  time,  too  hard  or 
not  hard  enough.  (7)  Allowing  shaken  mixture  to 
stand  too  long  before  whirling.  (8)  Running  centri- 
fuge too  slow  or  too  fast,  or  for  a  longer  or  shorter 
time  than  7^  or  8  minutes.  (9)  The  use  of  a  revolv- 
ing wheel  greater  or  less  than  15  inches  without  a  cor- 
responding change  in  the  number  of  revolutions.  (10) 
Reading  the  results  in  less  than  10  minutes  after  whirl- 
ing, (n)  Any  condition  which  disturbs  the  distinct 
flatness  of  the  upper  or  lower  surface  of  the  cylindrical 
column  of  compacted  casein. 


CHAPTER  XXIX 

Cheese-Factory  Management 

STATEMENT  FOR  PATRONS 

Whenever  a  dividend  is  made,  each  patron  should 
receive  with  the  dividend  a  statement  containing  all 
necessary  items,  which  will  enable  each  patron  to 
calculate  the  dividend  and  satisfy  himself  that  no 
errors  have  been  made.  It  is  convenient  to  use  a 
printed  blank  form  for  making  such  statements  to 
patrons.  The  form  given  below  is  suggested  as  cov- 
ering all  important  points,  but  one  much  simpler  may 
usually  answer  the  purpose.  It  is  also  highly  de- 
sirable that  a  general  statement  be  issued  at  the  close 
of  the  season,  giving  a  summary  of  the  whole  season's 
work. 

Statement  of Cheese- 
Factory. 

1.  Name  of  patron 

2.  Statement  for  month  of  (or  whatever  the  period  of  time  is) 19.... 

3.  Sales  include  dates  from to 

4.  Number  of  pounds  of  cheese  in  sale  (or  sales) 

5.  Number  of  pounds  of  milk  represented  in  sale  (or  sales) 

6.  Amount  of  money  received $ 

7.  Price  received  per  pound  for  cheese  (at  each  sale,  and  average  if  more 

than  one) cents 

8.  Expenses  deducted $ 

9.  Balance  for  dividends  $ 

10.  Net  value  of  one  pound  of  milk  (weight-of-milk  basis) cents 

11.  Number  of  pounds  of  milk  delivered  by  you 

12.  Value  of  milk  delivered  by  you $ 

13.  Total  number  of  pounds  of  milk-fat   represented   in  sale  (when    fat' 

basis  is  used) 

14.  Average  percent  of  milk-fat  in  milk    per  cent 

15.  Net  value  of  one  pound  of  milk-fat cents 

451 


452     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


16  Average  per  cent  of  milk  fat  in  milk  delivered  by  you 

17.  Number  of  pounds  of  milk  fat  delivered  by  you 

18.  Value  of  milk-fat  delivered  by  you 

19.  Debtor  by pounds  of  cheese  at cents  per  pound 

20.  Money  due  you 

21.  Number  of  pounds  of  cheese  made  from  100  pounds  of  milk 

22.  Number  of  pounds  of  milk  required  to  make  one  pound  of  cheese 

23.  Number  of  pounds  of  cheese" made  for  one  pound  of  fat  in  milk 


BUSINESS   MANAGEMENT   OR   ORGANIZA- 
TION OF  A  CHEESE-FACTORY 

The  business  management  of  a  cheese-factory  is 
generally  carried  on  according  to  one  of  two  sys- 
tems; in  one  case  the  ownership  of  the  factory  is 
private,  while,  in  the  other,  it  is  vested  in  a  stock 
company. 

In  the  case  of  private  ownership  of  the  cheese- 
factory,  the  owner  receives  a  certain  price  per 
pound  for  making  the  cheese  and  is  responsible 
for  all  expenses  connected  with  the  operations  of 
cheese-making.  The  milk  and  cheese  are  regarded 
as  the  property  of  the  patrons  and  they  have  some 
organized  arrangement  for  selling  the  cheese  and 
distributing  the  money.  In  some  cases  where  the 
ownership  of  the  factory  is  private,  the  milk  is 
contracted  for  at  a  certain  price  and  then  the 
patrons  have  nothing  to  do  with  the  business  man- 
agement. 

When  a  cheese-factory  is  owned  by  a  stock-com- 
pany, the  patrons  are  the  stockholders.  They  form  a 
definite  organization  and  through  chosen  officers  carry- 
on  the  entire  business  management  from  the  hiring  of 
a  cheese-maker  to  the  sale  of  the  cheese. 

Preliminary  steps  in  establishing  a  co-operative 
cheese-factory. — When  a  community  is  considering 
the  question  of  organizing  a  stock-company  for  the 


CHEESE-FACTORY   ORGANIZATION  453 

purpose  of  building  and  running  a  cheese-factory, 
the  first  point  to  be  ascertained  is  the  number  of 
cows  which  can  be  utilized  as  a  source  of  milk  sup- 
ply. This  information  can  be  gained  only  by  a 
careful  personal  canvass.  In  general,  it  may  be 
said  that  no  attempt  should  be  made  to  establish 
a  factory  unless  at  least  150  cows  within  a  radius 
of  3  or  4  miles  can  be  relied  upon  to  furnish  milk. 
Dairymen  should  be  on  their  guard  against  so- 
called  factory  "sharks/'  a  name  applied  to  repre- 
sentatives of  supply  houses  who  make  a  business 
of  promoting  co-operative  factories  and  creameries. 
The  promoter  makes  exaggerated  representations 
of  the  profits  of  cheese-making  for  dairymen  with- 
out reference  to  the  number  of  available  cows. 
When  he  is  successful  in  persuading  farmers  to 
organize  a  company,  he  attends  to  the  building  and 
equipment,  turning  over  the  plant  to  the  farmers  at 
a  price  which  nets  him  one  to  two  thousand  dollars. 
Before  erecting  a  cheese-factory,  inquiry  for  plans 
and  cost  should  be  made  of  the  state  department  of 
agriculture  or  of  the  nearest  agricultural  college. 
In  general,  it  will  be  found  .safe  and  profitable  to 
have  nothing  whatever  to  do  with  any  traveling 
agents. 

Formation  of  a  cheese-factory  company  or  as- 
sociation.— After  a  successful  canvass  has  been 
made  and  there  have  been  obtained  signed  agree- 
ments to  furnish  milk  from  a  certain  number  of 
cows,  on  the  part  of  those  who  intend  to  join  the 
association,  a  meeting  should  be  called  for  organi- 
zation. The  money  may  be  raised  either  by  indi- 
vidual pledges  to  purchase  a  certain  number  of 


454     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

shares  of  stock  at  a  certain  price ;  or  an  elected  board 
of  directors  may  be  authorized  to  borrow  the  amount 
of  money  needed,  the  debt  being-  discharged  by  taking 
a  fixed  proportion  from  the  dividends  of  the  associa- 
tion members. 

Articles  of  agreement  or  constitution  and  by- 
laws.— When  it  has  been  decided  to  form  a  cheese- 
factory  association,  it  is  necessary  to  prepare  an 
agreement  to  be  signed  by  all  the  members;  this 
agreement  embodies  the  details  of  organization, 
usually  in  the  form  of  a  constitution  and  by-laws. 
Different  conditions  will  call  for  differences  in  the 
details  of  such  an  agreement.  Suggestions  can  be 
given  here,  but  they  will  need  modification  and 
adaptation  to  suit  the  conditions  peculiar  to  each 
association. 

(1)  Name    and    object. — This    association     shall 

be  known  as  the Cheese- Factory 

Co-operative    Company;     its    object    is   to   manufac- 
ture    cheese     from     normal     (whole)     milk.       The 
undersigned  agree  to  become  members  of  said  com- 
pany. 

(2)  Capital  stock.-r-The  capital  stock  of  the  com- 
pany shall  be  $ ,  divided  into 

shares  of  $. . . : each. 

(3)  Officers. — The  officers  of  the  company  shall 
be    a    president,    a    secretary    and    a    treasurer,    and 
these,    with   three   other   members    of   the   company, 
shall    constitute    a    board    of    directors.     These    offi- 
cers shall  be  elected  by  ballot  at  the  annual  meet- 
ing  and    shall    hold    office    one    year    or   until    their 
successors  have  been   elected   and  qualified.     Vacan- 
cies   in    the    board    may   be    filled    by    the    directors 


CHEESE-FACTORY    ORGANIZATION  455 

for  the  time  ensuing  until  the  next  annual  election. 
(4)  Duties  of  officers.— (i)  The  president 
shall  preside  at  all  meetings  of  the  company  and 
of  the  board;  in  his  absence,  some  other  member 
of  the  board  shall  preside.  He  shall  perform  such 
other  duties  as  may  be  indicated.  All  documents, 
drafts,  etc.,  involving  the  interests  of  the  com- 
pany, shall  be  signed  by  the  president.  He  shall 
call  special  meetings  when  necessary.  (2)  The 
secretary  shall  keep  an  accurate  record  of  all  pro- 
ceedings of  the  meetings  of  the  company  and  of 
the  board.  He  shall  issue  notices  of  meetings,  ap- 
pointments on  committees,  statements  to  patrons, 
etc. ;  he  shall  sign  all  papers,  carry  on  the  cor- 
respondence, etc.  (3)  The  treasurer  shall  receive 
and  disburse  the  money  of  the  company.  He  shall 
give  receipt  for  all  money  belonging  to  the  asso- 
ciation. He  shall  make  out  dividends,  etc.  He 
shall  pay  out  money  only  upon  orders  signed  by 
the  president  and  secretary.  He  shall  keep  a  cor- 
rect financial  account  between  the  company  and 
its  members.  He  shall  keep  a  proper  set  of  books, 
which  shall  be  open  for  inspection  to  members  of 

the  company.     He  shall  give  bonds  for  $ 

(4)  The  board  of  directors  shall  elect  one  of  their 
number  as  general  business  manager  of  the  com- 
pany, who  shall  be  responsible  for  the  conduct  of 
the  business  details  of  the  company.  The  board 
shall  appoint  any  needed  agents,  manage  the  com- 
pany's investments,  audit  all  accounts  and  fix  com- 
pensation for  services  in  all  cases.  They  shall  make 
regulations  and  enforce  them.  They  shall  arrange 
for  the  keeping  of  a  record  of  all  necessary  details, 


456     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

such  as  weights  of  milk  delivered  daily  by  each 
member,  fat-test  of  the  same,  the  amounts  of  cheese 
made  day  by  day,  the  sales  of  cheese,  current  ex- 
penses, etc.  They  shall  distribute  monthly  among 
the  members  or  patrons  the  money  due  them. 
They  shall  make  a  complete  statement  at  the  annual 
meeting  covering  for  the  year  all  matters  relating  to 
the  business  of  the  company.  Meetings  of  the  board 
may  be  called  by  the  president  or  by  any  two  of  its 
members. 

(5)  Meetings. — The   regular   annual   meetings   of 
the  company  shall  be   held  on  the   first  Tuesday  of 
the  month  of Special  meet- 
ings  may  be  called  by  the   president  or   on   written 
request   of   ten   members   of   the   company.     Written 
notices    for    all    special    meetings    must    be    sent    to 
each  member  of  the  company  three  days  in  advance 
of    such   meeting.       In    addition    to    the   election    of 
officers    and    presentation    of    reports,    the    members 
shall  decide  by  majority  vote  at  the  annual  meeting 
in  what  manner  the  dividends  shall  be  made  (weight- 
of-milk,  fat-basis,  etc.). 

(6)  Regulations. — The   following  are  samples  of 
what  regulations  may  be  made:     (a)    The  price  for 

making  cheese  shall  be cents  a  pound. 

(b)     Members  shall  be  held  responsible  for  furnish- 
ing milk  from  the  number  of  cows   promised,     (c) 
The     cheese-maker     may    reject     such     milk     as     is 
tainted   or   of   too   high    acidity   or   is   any   way   un- 
suited  to  make  high-grade  cheese,     (d)     Milk  must 
not  be  received  unless  it  has  been  properly  strained 
and   delivered   at  the   factory   at   a   temperature   not 
above degrees  F.     (e)    The  milk  of  each 


CHEESE-FACTORY   ORGANIZATION  457 

patrons  shall  be  tested  for  its  percentage  of  fat  not 
less  often  than  once  in  10  days,  (f)  A  testing-com- 
mittee consisting  of  the  secretary  or  treasurer,  one 
other  director  and  one  member  not  an  officer  shall 
assist  the  cheese-maker  in  testing  the  milk,  (g)  A 
patron's  premises  may  be  inspected  by  order  of 
the  board  to  ascertain  the  suitability  of  the  conditions 
for  producing  and  caring  for  clean  milk.  The  board 
may  order  samples  of  milk  taken  at  patron's  farm 
when  desired,  (h)  No  patron  shall,  in  any  manner, 
adulterate  milk  to  be  taken  to  the  factory,  as  by  water- 
ing, skimming,  addition  of  preservative,  etc.  No 

patron  shall  take  more  than pounds  of  whey  for 

loo  pounds  of  milk  delivered. 

(7)  Voting  power. — Members  may,  at  all  meet- 
ings of  the  company,  be  entitled  to  one  vote  for  each 
1,000  pounds  of  milk   furnished  by  him  during  the 
preceding  season  or  during  the  preceding  portion  of 
the  current  season,  as  shown  by  the  records;   or  each 
may  have  one  vote  for  each  share  of  stock  owned  by 
him. 

(8)  Amendments. — Any  changes  or  amendments 
to  the  constitution  or  by-laws  may  be  made  in  writing 
and   posted   conspicuously   in   the   cheese-factory   one 
month  previous  to  action  upon  them.     Two-thirds  vote 
of  the  stockholders  is  required  to  make  such  changes. 


CHAPTER  XXX 

The  Literature  of  Cheese-Making 

It  is  desirable  to  give  references  to  the  literature 
of  cheese-making  for  the  benefit  of  those  who  wish 
to  go  to  original  sources  of  information.  In  pre- 
paring the  list  given  below,  the  aim  is  mainly  to 
cover  the  ground  represented  in  the  subject-matter 
of  the  book.  A  selection  has  been  made  of  what 
may  be  regarded  as  the  most  useful  material  for 
this  purpose,  no  attempt  being  made  to  present 
an  exhaustive  list  of  everything  written  on  the 
subject. 

In  order  to  render  the  material  most  readily 
available  for  reference,  the  following  plan  is 
adopted :  There  is  first  given  a  continuously 
numbered  list  of  the  publications  referred  to;  the 
arrangement  is,  first,  by  institutions  and  then 
under  each  the  individual  articles  are  given  in 
chronological  order.  Then  follows  an  index  of 
the  subjects  treated  in  this  list  of  publications. 
It  is  believed  that  this  plan  will  prove  the  most 
useful  in  enabling  anyone  to  consult  the  literature. 

PUBLICATIONS  RELATING  TO  CHEESE-MAKING 
Cornell  University  Experiment  Station,  Ithaca,  N.  Y. 

1  1st  Ann.  Rept.  (1879-80).    Experiments  upon  the  cur- 
ing of  cheese  (pp.  9-27).      Babcock. 

2  Bui.  85  (March,  1895).     Whey-butter.     Wing. 

3  Bui.    158  (Jan.,    1899).     Sources   of    gas    and  taint- 
producing  bacteria.     Moore  and  Ward. 

4  Bui.  178  (Jan.,  1900).     The  invasion  of  the  udder  by 
bacteria.     Ward. 

5  Bui.    203   (July,    1902).     The   care  and  handling  of 
milk.      Hunziker. 

458 


THE    LITERATURE    OF     CHEESE-MAKING  459 

Iowa  Agricultural  College  Experiment  Station,  Ames,  Iowa 

6  Bui.    21    (1893).     Investigations    in    cheese -making 
(pp.  751-767).     Wallace. 

7  Bui.  24  (1894).     Changes  during  cheese -ripenine  (DO 
969-984).      Patrick. 

8  Bui.     57     (1901).     Experiments    in    curing    cheese. 
McKay. 

Michigan  State  Agricultural  College  Experiment  Station, 
East  Lansing,  Mich. 

9  Special    Bui.    16    (June,    1902).     Aeration    of    milk. 
Marshall.  *' 

10  Special    Bui.    21    (Sept.,    1903).     Cheese    problems: 

(a)  Relation  of  yield  of  cheese  and  per  cent  of  fat  in  milk. 

(b)  Paraffining   cheese,     (c)  Cheddar   vs.    stirred   curd,      (d) 
Cheese-ripening  as  affected   by  temperature    and   moisture. 
(<?)  Sage  cheese,     (f)  Gassy  milk.     Michels. 

11  Special  Bui.  23  (Jan.,  1904).     A  preliminary  note  on 
the  associative  action  of  bacteria  in  the  souring  of  milk  and 
in  other  milk  fermentations.     Marshall. 

12  Special  Bui.  29  (May,  1904).     Additional  work  upon 
the  associative  action  of  bacteria  in  the  souring  of  milk  and 
in  other  milk  fermentations.     Marshall. 

13  Special  Bui.  33  (June,  1905).     Extended  studies  of 
the  associative  action  of  bacteria  in  the  souring  of  milk. 
Marshall. 

14  Special  Bui.  42  (March,   1908).     Bacterial  associa- 
tions in  the  souring  of  milk.     Marshall. 

15  Bui.    183    (June,    1900).     Gassy   curd   and   cheese. 
Marshall. 

16  Bui.  201  (June,  1902).     Aeration  of  milk.     Marshall. 

Minnesota  Agricultural  Experiment  Station,  St.  Anthony  Park, 
Minnesota 

17  Bui.  19  (Jan.,  1892).     Experiments  in  cheese-mak- 
ing.    Incorporating  cream  into  cheese  (pp.  20-25).     Snyder. 

18  Bui.  27  (Feb.,  1893).     Losses  of  milk-solids  in  cheese- 
making  (pp.  57-62).     Snyder. 

19  Bui.   35   (Oct.,    1894).     Manufacture  of  sweet -curd 
cheese.      Haecker. 

New  York  Agricultural  Experiment  Station,  Geneva,  N.  Y. 

20  Bui.  37  (Nov.,  1891)  and  10th  Ann.  Kept.  (pp.  220- 
299).     Investigation  of  cheese:  (a)  Experiments  in  the  manu- 
facture of  cheese.     (6)   Influence  of  composition  of  milk  on 
composition  and  yield  of  cheese,     (c)  A  study  of  the  process 
of  ripening  of  cheese.      Van  Slyke. 


460    SCIENCE    AND    PRACTICE   OF    CHEESE-MAKING 

21  Bui.  43  (June,   1892).     Experiments  in  the   manu 
facture  of  cheese  during  May.      Van  Slyke. 

22  Bui.   45   (Aug.,   1892).     Experiments  in  the  manu- 
facture of  cheese  during  June.      Van  Slyke. 

23  Bui.  46  (Sept.,   1892).     Experiments  in  the  manu- 
facture of  cheese  during  July  and  August.      Van  Slyke. 

24  Bui.  47   (Nov.,    1892).      Experiments  in  the  manu- 
facture of  cheese  during  September  and  October.     Van  Slyke. 

25  Bui.  50  (Jan.;  1893)  and  llth  Ann.  Rept.  (pp.  299- 
467).     Summary  of  the  results  of  experiments  made  in  the 
manufacture  of  cheese  during  the  season  of  1892.     Van  Slyke 

26  Bui.  54  (May,  1893)  and  12th  Ann.  Rept.  (pp.  276 
319).     Experiments  in  the  manufacture  of  cheese:     Part  1 
Manufacture  of  cheese  from  normal  milk  rich  in  fat.     Part  IT, 
Study  of  cheese -ripening  process.      Van  Slyke. 

27  Bui.  56  (May,  1893)  and  12th  Ann.  Rept.  (pp.  244- 
275).     Experiments  in  the  manufacture  of  cheese:     Part  I, 
The  manufacture  of  Edam  cheese.     Part  II,  The  manufacture 
of  Gouda  cheese.      Van  Slyke. 

28  Bui.  60  (Oct.,   1893).     Investigation  relating  to  the 
manufacture  of  cheese.     Part  I,  Results  of  work  done  in  the 
No.   1    factory  of    E.  L.  Stone  at  Mannsville,  Jefferson  Co., 
during  the  season  of  1893.      Van  Slyke. 

29  Bui.  61  (Nov.,  1893).     Investigation  relating  to  the 
manufacture  of  cheese.     Part  II,  Results  of  work  done  in  the 
factory  of  G.  Merry  at  Verona,  Oneida  Co.,  N.  Y.,  during  the 
season  of  1893.      Van  Slyke. 

30  Bui.  62  (Dec.,  1893).     Investigation  relating  to  the 
manufacture   of   cheese.     Part    III,    Results   of    Work   done 
during  the  season  of  1893  in  48  different  factories,  located 
in  8  different  counties.      Van  Slyke. 

31  Bui.  65  (Jan.,  1894)  and  12th  Ann.  Rept.  (pp.  319- 
486).     Investigation  relating  to  the  manufacture  of  cheese. 
Part  IV,  Summary  of  the  results  of  work  done  in  cheese- 
factories  during  the  seasons  of  1892-3.      Van  Slyke. 

32  Bui.    68   (March,    1894).     Investigation   relating  to 
the  manufacture  of  cheese.     Part  V,  Fat  in  milk  as  a  practical 
basis  for  determining  the  value  of  milk  for  cheese -making. 
Van  Slyke. 

33  Bui.    71    (May,    1894).     Some    reasons    why    there 
should  be  a  legal   standard  for  cheese  in  New  York  state. 
Van  Slyke. 

34  Bui.  79  (Nov.,  1894)  and  13th  Ann.  Rept.  (pp.  351- 
379).     Comparison  of  different  breeds  of  cattle.     The  cost  of 
cheese  production-      Van  Slyke. 


THE    LITERATURE    OF     CHEESE-MAKING  461 

35  Bul.  82  (Dec.,  1894)  and  13th  Ann.  Kept.  (pp.  452- 
522).     Results  of  investigation  relating  to  the  manufacture 
of  cheese  for  the  season  of  1894.      Van  Slyke. 

36  Bul.  105  (Aug.,  1896)  and  15th  Ann.  Rept.  (pp.  37- 
65).     Effects  of  drouth  upon  milk  and  cheese  production. 
Van  Slyke. 

37  Bul.  110  (Oct.,  1896)  and  15th  Ann.  Rept.  (pp.  66- 
106).     Milk-fat  and  cheese  yield.      Van  Slyke. 

38  Bul.  183  (Dec.,  1900)  and  19th  Ann.  Rept.  (pp.  29- 
51).     Notes  on  some  dairy  troubles:    (a)  Flavor  in  milk  and 
its  products.     (6)   Fishy  flavor  in  milk,     (c)   Bitter  flavor  in 
Neufchatel    cheese.      (d)  Sweet    flavor    in    cheddar    cheese. 
(e)    Rusty   spot    in   cheddar   cheese.      Harding,    Rogers  and 
Smith. 

39  Bul.  184  (Dec.,  1900)  and  19th  Ann.  Rept.  (pp.  251- 
260).     The  influence  of  the  temperature  of  curing  upon  the 
commercial  quality  of  cheese.     Smith. 

40  Bul.  203  (Dec.,  1901)  and  20th  Ann.  Rept.  (pp.  165- 
193).     A  study  of  enzyms  in  cheese.      Van  Slyke,   Harding 
and  Hart. 

41  Bul.    207    (Dec.,    1901)    and    20th  Ann.  Rept.  (pp. 
194-219).     Conditions  affecting  weight  lost  by  cheese  in  cur- 
ing.     Van  Slyke. 

42  Bul.  225  (Dec.,  1902)  and  21st  Ann.  Rept.  (pp.  27- 
53).     Control  of  rusty  spot  in  cheese-factories.      Harding  and 
Smith. 

43  Bul.  231  (Feb.,  1903)  and  22d  Ann.  Rept.  (pp.  165- 
187).     The  relation  of   carbon   dioxid  to   proteolysis  in  the 
ripening  of  cheddar  cheese.      Van  Slyke  ana  Hart. 

44  Bul.  233  (June,  1903)  and  22d  Ann.  Rept.  (pp.  188- 
217).     Rennet  enzym  as  a  factor  in  cheese-ripening.      Van 
Slyke,  Harding  and  Hart. 

45  Bul.  234  (July,  1903)  and  22d  Ann.  Rept.  (pp.  218- 
242).     Experiments  in  curing  cheese  at  different  tempera- 
tures.     Van  Slyke,  Smith  and  Hart. 

46  Bul.  236  (July,  1903)  and  22d  Ann.  Rept.  (pp.  243- 
273).     Conditions     affecting    chemical    changes    in    ch  ^ese- 
ripening.      Van  Slyke  and  Hart. 

47  Bul.  261  (Jan.,  1905)  and  24th  Ann.  Rept.  (pp.  238- 
271).     Some  of  the  relations  of  casein  and  paracasein  to  bases 
and  acids   and  their  application   to  cheddar   cheese.      Van 
Slyke  and  Hart. 

48  Technical  Bul.  3  (Dec.,  1906)  and  25th  Ann.  Rept. 
(pp.    203-286).     I,   The  action  of   dilute  acids  upon  casein 
when  no  soluble  compounds  are  formed.     II,  The  hydrolysis 
of  the  sodium  salts  of  casein.      Van  Slyke  (L.  L.~)  and  Van 
Slyke  (D.  D.). 


462     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

49  Technical  Bui.  4  (April,  1907).     I,  Some  of  the  first 
chemical  changes  in  cheddar  cheese.     II,  The  acidity  of  the 
water-extract  of  cheddar  cheese.      Van  Slyke  and  Bosworth 

50  Technical  Bui.   6  (Dec.,   1907).     Chloroform  as  an 
aid  in  the  study  of  milk-enzyms.      Harding  and  Van  Slyke. 

Oregon  Agricultural  Experiment  Station,  Cornwallis,  Ore. 

51  Bui.  78  (March,  1904).     Canning  cheese.     Pernot. 

U.  S.  Department  of  Agriculture,  Bureau  of  Animal  Industry, 
Dairy  Division,  Washington,  D.  C. 

52  Bui.  11  (Nov.,  1895)  and  55  (Feb.,  1903).     Statistics 
of  the  dairy.      Alvord. 

53  Bui.   15  (Oct.,   1896).     The  cheese  industry  of  the 
state  of  New  York.      Gilbert. 

54  Bui.  17  (Nov.,  1896).     Dairy  schools.      Pearson. 

55  Bui.   49   (June,    1903).     The  cold-curing  of  cheese. 
Report  upon  experiments  conducted  under  the  auspices  of 
the  U.  S.  Department  of  Agriculture,  Bureau  of  Animal  In- 
dustry, Dairy  Division,  in  co-operation  with  the  Wisconsin 
Agricultural  Experiment  Station  and  the  New  York  Agri- 
cultural Experiment  Station.     Alvord. 

56  Bui.  62  (July,   1904).     The  relation  of  bacteria  to 
the  flavors  of  cheddar  cheese.     Rogers. 

57  Bui.  75  (Sept.,  1905).     Records  of  dairy  cows  in  the 
United  States.     Lane. 

58  Bui.  83  (March,  1906).     The  cold  storage  of  cheese. 
Lane. 

59  Bui.  85  (May,  1906).     The  cold-curing  of  American 
cfteese.     Doane. 

60  Bui.  105  (Jan.,  1908).     Varieties  of  cheese:  descrip- 
tions and  analyses.     Doane  and  Lawson. 

61  Bui.  110  (Nov.  1908).     Development  of  lactic  acid 
in  cheddar  cheese-making.     Doane. 

Utah  Agricultural  Experiment  Station,  Logan,  Utah 

62  Bui.  73  (Aug.,  1901).     Experiments  in  cheese-mak- 
ing (pp.  41-54).      Linfield. 

63  Bui.  96  (March,  1906).     Canning  cheese.    Paraffining 
cheese  (pp.  128-132).     Clark  and  Crockett. 

Vermont  Agricultural  Experiment  Station,  Burlington,  Vt. 

64  5th    Ann.    Rept.  (1891).     (a)  Making  cheese  from 
different  qualities  of  milk  (pp.  88-95).     (6)  Losses  in  cheese- 
making  (pp.  95-100).     Cooke  and  Hills. 


THE    LITERATURE    OF     CHEESE-MAKING  463 

Wisconsin  Agricultural  Experiment  Station,  Madison,  Wis. 

65  8th  Ann.  Rept.  (1891).     The  feeding  value  of  whey 
(pp.  38-48).      Henry. 

66  llth  Ann.  Rept.  (1894).     (a)   Influence  of  fat  upon 
yield  of  chefcse  (pp.  131-134).     (6)   Influence  of  fat  on  quality 
of  cheese  (pp.  134-137).     (c)  Yield  of  cheese  in  factories  from 
different  qualities  of  milk  and  at  different  seasons  (pp.  137- 
144).    (d)   Loss  in  curing  cheese  (pp.  145-146).     (e)  Cleaning 
milk  with  a  centrifugal  cream-separator  for  cheese  production 
(pp.  146-149).     Babcock. 

(/)  Sources  of  bacterial  contamination  of  milk  (pp.  150- 
165).  Russell. 

(g)  Effect  of  salt  upon  cheese  (pp.  220-222).     Decker. 

67  12th  Ann.  Rept.  (1895).     (a)  The  centrifugal  sepa- 
ration of  casein  and   insoluble   phosphates   from  milk  (pp. 
93-99).    (6)  Relation  between  yields  or  milk-solids  and  cheese 
(pp.    100-120).     (c)   Relation    between    specific    gravity  and' 
solids  of  milk  (pp.  120-126).     (d)   Hot  iron  test  (pp.  133-134). 
(e)  Albumen  cheese  (pp.  134-136).      Babcock. 

(/)  Effect  of  aeration  on  flavor  of  tainted  curds  in  cheese- 
making  (pp.  127-129).  (g)  Gas-producing  bacteria  and  their 
relation  to  cheese  (pp.  139-150).  Russell. 

(ti)  Influence  of  acid  on  texture  of  cheese  (pp.  129-133). 
Russell  and  Decker. 

(i)  Ripening  milk  before  setting  (pp.  136-138).     Decker. 

68  13th  Ann.  Rept.  (1896).     (a)   Rise  and  fall  of  bac- 
teria in  cheddar  cheese  (pp.   95-111).     (6)   Pure  lactic  acid 
cultures  in  cheese-making  (pp.  112-126).      Russell. 

(c)  Moisture  supply  in  cheese-curing  rooms  (pp.  156- 
163).  Decker. 

69  14th  Ann.  Rept.  (1897).     (a)  Unorganized  ferments 
of  milk:    a  new  factor  in  the  ripening  of  cheese  (pp.  161-193). 
(6)  Influence  of  temperature  on  the  ripening  of  cheese  (pp. 
194-210).     Babcock  and  Russell. 

70  Bui.  60  (May,  1897).     The  cheese  industry:    its  de- 
velopment and  possibilities  in  Wisconsin.     Babcock  and  Rus- 
sell. 

71  Bui.  61  (Sept.,  1897).     The  constitution  of  milk  with 
especial  reference  to  cheese-production.     Babcock. 

72  Bui.  62  (Sept.,  1897).     Tainted  or  defective  milks. 
Their  causes  and  methods  of  prevention.     Russell. 

73  15th    Ann.    Rept.    (1898).     (a)  Effect    of    varying 
strengths  of  rennet  in  curdling  milk  (pp.  31-34).     (6)  Action 
of  rennet  in  watered  milk  (pp.  35-36).     (c)  Action  of  common 
salt  on  rennet  action  (pp.  37-41).     (d)  Methods  of  handling 
sour  milk  in  making  cheese  (pp.  42-44).     Decker 


464     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

(e)  Improved  curd  test  for  detection  of  tainted  milks 
(pp.  45-53).  Babcock,  Russell  and  Decker. 

(/)  Properties  of  galactase,  a  digestive  ferment  of  milk 
(pp.  77-87).  (g)  Distribution  of  galactase  in  cow's  milk 
(pp.  87-92).  Babcock,  Russell  and  Vivian. 

(h)  Relative  absorption  of  odors  in  warm  and  cold  milk 
(pp.  104-109).  Russell. 

74  16th  Ann.   Kept.  (1899).     (a)  Coating  cheese  with 
paraffin  (pp.  153-155).     Decker. 

(b)  Action  of   proteolytic  ferments  on  milk  with  special 
reference  to  galactase,  the  cheese-ripening  enzym  (pp.   155- 
174).      Babcock,  Russell  and  Vivian. 

(c)  Effect    of   digesting  bacteria   on   cheese-solids   (pp. 
/187-193).      Russell  and  Bassett. 

75  17th   Ann.    Rept.    (1900).     Influence   of   rennet   on 
cheese-ripening  (pp.  102-122).     Babcock,  Russell  and  Vivian. 

76  18th  Ann.  Rept.  (1901).     (a)   Print  cheese  (pp.  132- 
135).      Farrington. 

(b)  Influence  of  cold-curing  on  quality  of  cheese  (pp. 
136-161).      Babcock,  Russell,  Vivian  and  Baer. 

(c)  Influence   of    sugar    on    nature    of    fermentation    in 
milk  and  cheese  (pp.  162-176).     Babcock,  Russell,  Vivian  and 
Hastings. 

77  19th    Ann.    Rept.    (1902).     (a)   Influence    of    cold- 
curing  on  quality  of  cheddar  cheese  (pp.  150-164).     (b)   Influ- 
ence of  temperature  approaching  60°F.    on  development  of 
flavor  in   cold -cured  cheese  (pp.   165-173).     (c)   Influence  of 
varying  quantities  of  rennet  on  cold-cured  cheese  (pp.  174- 
179).     (d)  Conditions  affecting  development  of  white  specks 
in  cold-cured  cheese  (180-184).     Babcock,  Russell,  Vivian  and 
Baer. 

78  Bui.    94   (Aug.,    1902).     Curing   of   cheddar   cheese 
with   reference  to   cold-curing.      Consolidated   cheese-curing 
stations.      Babcock  and  Russell. 

79  Bui.    101     (July,    1903).     Shrinkage    of    cold-cured 
cheese  during  ripening.     Experiments  in  paraffining  cheese. 
Babcock,  Russell  and  Baer. 

80  21st  Ann.  Rept.  (1904).     (a)   Relation  of  flavor  de- 
velopment in  cold-cured  cheddar  cheese  to  bacterial  life  in 
same  (pp.  155-163).      Russell  and  Hastings. 

81  Bui.    115   (Sept.,   1904).     The  quality  of  cheese  as 
affected  by  rape  and  other  green  forage  plants  fed  to  dairy 
cows.     Baer  and  Carlyle. 

82  22d  Ann.   Rept.  (1905).     (a)  The  Swiss  cheese  in- 
dustry  of    Wisconsin;    whey  butter-making    (pp.    157-180). 
Farrington. 


THE    LITERATURE    OF    CHEESE-MAKING  465 

(6)  Lactose-fermenting  yeasts,  the  cause  of   abnormal 
fermentation  in  Swiss  cheese  (pp.  207-221).      Hastings 

83  Bui.    128    (Sept.,    1905).     A   Swiss   cheese   trouble 
caused  by  a  gas-forming  yeast.     Russell  and  Hastings. 

84  Bui.  132  (Dec.,  1905).     The  manufacture  of  whey- 
butter  at  cheese-factories.      Farrington. 

85  23d  Ann.  Rept.  (1906).     (a)  Development  of  factory 
dairying  in  Wisconsin  (pp.  100-106).     Russell  and  Baer. 

(b)  Distribution   of   lactose-fermenting   yeasts   in   dairy 
products  (pp.  107-115).      Hastings. 

86  24th  Ann.  Rept.  (1907).     (a)   Influence  of  metals  on 
the  action  of  rennet  (pp.  134-159).      Olson. 

(b)  Analyses  of  old  cheese,  skim-milk  cheese,  etc.  (pp. 
160-170).     Wall  and  Olson. 

87  Bui.  162  (April,  1908).     Rusty  cans  and  their  effect 
upon  milk  for  cheese-making.      Olson. 

Dominion  of  Canada  Dairy  Commission,  Department  of 
Agriculture,  Ottawa,  Can. 

88  2d  Ann.  Rept.  ( 1 89 1  -2) .     Experimental  cheese-mak- 
ing (pp.  146-153).      Robertson  and  Ruddick. 

89  3d  Ann.   Rept.   (1892-3).     Experiments  in  cheese- 
making  (pp.  214-219).      Robertson  and  Ruddick. 

90  Rept.   Conference   Dairy    Instructors   and   Experts 
(1903).     The  cool-curing  of  cheese  (pp.  96-110).     Ruddick. 

91  Rept.  of  Dairy  Com'r  (1906).     (a)  Cool-cured  cheese 
(pp.  8-9).     (o)  Management  of  a  cool  curing-room  (pp.  13-14). 
(c}  Coating  cheese  with  paraffin  (pp.  14-15).     Rudatck. 

92  Rept.  of  Dairy  Com'r  (1907).     (a)   The  cheese  indus- 
try (pp.  8-17).     (6)  Cool-cured  cheese  (pp.  17-18).     Ruddick. 

Ontario  Agricultural    College,  Guelph,  Ontario,  Canada 

93  Buls.  95  and  96  (1894)  and  20th  Ann.  Rept.  (1894). 
(a)  The  composition  of  milk,  whey  and  cheese  in  relation  to 
one  another  (pp.  20-33).     Shuttleworth. 

(b)  Experiments  in  cheese-making  (pp.  134-141).    Dean. 

94  Bui.   102  (May,   1896)  and  22d  Ann.  Rept.  (1896), 
(pp.  41-56).     Experiments  in  cheese-making.     Dean. 

95  23d  Ann.  Rept.  (1897).     (a)  Experiments  in  cheese- 
making  (pp.  41-59).     Dean. 

(b)  Bad  flavor  in  cheese  caused  by  undesirable  bacteria 
in  water  used  in  factory  (pp.  141-144).      Harrison. 

96  24th  Ann.   Rept.   (1898).     Experiments  in  cheese- 
making  (pp.  40-64).     Dean. 

97  25th  Ann.   Rept   (1899)      Experiments  in  cheese- 
making  (pp.  54-65).     Dean. 


466     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

98  26th  Ann.  Rept.   (1900).     Experiments  in    cheese- 
making  (pp.  37-44).  Dean. 

99  27th  Ann.  Rept.   (1901).     Experiments  in  cheese- 
making  (pp.  44-55).  Dean. 

100  28th    Ann.     Rept.     (1902).     (a)   Experiments     in 
cheese-making  (pp.  64-68).     Dean. 

(b)  Investigations  regarding  the  ripening  of  cheese  (pp. 
40-41).      Harcourt. 

101  Bui.    120   (May,    1902).     Bitter  milk  and  cheese. 
Harrison. 

102  Bui.  121  (June,  1902).     Ripening  of  cheese  in  cold 
storage  compared  with  ripening  in  ordinary  curing-rooms. 
Dean,  Harrison  and  Harcourt. 

103  29th  Ann.  Rept.  (1903).     Experiments  in  cheese- 
making  (pp.  60-76).     Dean. 

104  Bui.  130  (Dec.,  1903).     Bacterial  contents  of  cheese 
cured  at  different  temperatures.      Harrison  and  Connell. 

105  Bui.  131  (Dec.,  1903).     Ripening  of  cheese  in  cold- 
storage  versus  ordinary  curing-rooms.     Dean  and  Harcourt. 

106  30th  Ann.  Rept.  (1904).     Experiments  in  cheese- 
making  (pp.  74-81).     Dean. 

107  31st  Ann.  Rept.  (1905).     Experiments  in  cheese- 
making  (pp.  115-126).     Dean.* 

108  Bui.    141    (April,    1905).     Gas-producing   bacteria 
and  their  effect  on  milk  and  its  products.      Harrison. 

109  32d  Ann.  Rept.  (1906).     Experiments  in  cheese- 
making  (pp.  108-119).     Dean. 


Index  to  Literature  of  Cheese-Making 

The  reference  numbers  below  indicate  the  serial 
numbers  (in  heavy  type)  in  the  preceding  list  of  publi- 
cations, which  go  from  I  to  109. 

Acidity  of  water-extract  of  cheese 20,  49 

effect  on  texture  of  cheese 67 

Acid,  lactic,  development  of,  in  cheese-making 61 

pure  cultures  in  cheese-making 68 

milk,  handling  of,  in  cheese-making 73 

Acids,  action  upon  casein 48 

adsorption  by  casein 48 

effect  of,  on  enzyms  in  cheese 40,  44,  75,  77 

effect  of,  on  galactase  in  cheese-ripening 40,  74 

effect  of,  on  rennet  in  cheese-ripening 44,  75,  77 

phosphates  in  cheese 49 

relations  to  cheese-ripening 40,  44,  46 

Adsorption  of  acids  by  casein 48 

Aeration  of  milk 9,  16,  24,  25,  66 

of  milk  by  dipping 24 

of  milk  by  centrifugal  separator 24,  66 

Albumen  cheese 67 

Albumin  in   cheese 20-35 

in  milk 20-35 

in  whey 20-35 

lost  in  cheese-making 20-35 

relations  of,  to  casein  in  milk 20-35 

Amino  acids  in  cheese 40,  43,  46,  74-75,  77 

Ammonia  in  cheese 40,  43,  46,  74-75,  77 

Analyses  of  cheese 20-35,  40,  44-46,  49,  60,  75 

of  milk 20-35 

of  whey 20-35 

Bacteria,  associative  in  souring  of  milk 11-14 

digesting  and  cheese-solids 74 

in  udder 4,  40 

producing  gas  and  taints  in  cheese,  3,  10,  15,  67,  108 

producing  rust -red  spots  in  cheese 38,  42 

relation  of,  to  cheddar-cheese  flavors. .  .  .36,  67,  72 

rise  and  fall  of,  in  cheddar  cheese 68 

Bacterial  contamination  of  milk 66 

content  of  cheese  kept  at  different  temperatures,  104 

467 


468     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

Bitter  flavor  in  cheese  and  milk 46,  101 

Breeds  of  cattle,  comparative  value  of,  for  cheese  produc- 
tion  34 

Brine-soluble  protein  in  cheese 40,  44-46,  49 

Butter-fat  (see  Fat). 

Butter,  whey 2,  132 

Canning  cheese 51,63 

Casein,  action  of  acids  on 48 

action  of  rennet  and  pepsin  on 44 

adsorption  of  acids  by 48 

amount  in  cheese 20-35 

amount  in  milk 20-35 

amount  in  whey 20-35 

centrifugal  separation  of 67 

influence  on  composition  of  cheese 20-35 

influence  on  yield  of  cheese 20-35 

lost  in  cheese-making 20-35 

market  value  of,  in  cheese 32,  67 

relation  to  albumin  in  milk 20-35 

relation  to  fat  in  milk 20-35 

relation  to  fat  in  skim-milk 20-25 

relation  to  fat  in  skim -milk  cheese 20-25 

Centrifugal  separation  of  casein  from  milk 67 

Cheddar  and  stirred -curd  processes  compared 10,  20-25 

Cheese,  advantages  of  cold  storage,  8,  10,  41,  45,  55,  58-59, 

69,  76-80,  90-92,  102,  105 

albumin  in 20-35 

amino  acids  in 40,  43-46,  74-75,  77 

ammonia  in 40,  43-46,  74-75,  77 

analyses  of 6,  17,  20-35,40,43-46,49,  77,86 

canning  of 51,63 

casein  and  albumin  in 20-35 

central  curing-room  for 41,  78,  90-92 

cheddar  and  stirred-curd  processes  compared, 

10,  20-25 

chemical  changes  in  ripening  of 45-46 

chloroformed,  changes  in 40,  43-44 

cold-cured,  8,  10,  41,  45,  55,  58-59,  69,  76-80, 

90-92,  102,  105 

cold-cured,  composition  of 45 

cold-cured,  white  specks  in 77 

comparative  production  of,  by  different  breeds 

of  dairy  cattle 34 

composition  of 20-35,  40,  43-46 

composition  of,  in  relation  to  composition  of  milk, 

20-35 


INDEX    TO    LITERATURE    OF   CHEESE-MAKING      469 

Cheese — continued 

conditions  used  in  manufacturing  operations  of,  20-35 

consolidated  stations  for  curing 78 

cost  of  producing 34 

Edam,  manufacture  and  composition  of 19,  27 

effect  of  cold  storage  on  moisture  of,  45,  55,  58-59, 

78-79,  90-92,  102,  105 

effect  of  moisture  on  quality  of 41,  45,  46 

effect  of  paraffining.  .10,  45-46,  55,  58-59,  63,  79,  91 
effect  of  temperature  in  ripening,  8,  10,  39,  41, 

45-46,  55,  58-59,  69,  76-80,  90-92,  102,  105 
experiments  in  manufacture  of,  6,  10,  17,  19,  20-35, 
64,  67,  73,  81-82,  88-89,  93-100,  103,  106-1O7,  109 

fat  in 6,  10,  18,  20-35,  37,  64,  67,  93 

flavor  and  texture  of,  20-25,  39,  45,  46,  56,  66-67, 

76-78,  80,  93 

gassy 3,  10,  15,  67,  108 

Gouda,  manufacture  and  composition  of 19,  27 

industry  in  New  York 53 

industry  in  Wisconsin 70,  82,  85 

influence  of  milk  on  composition  of 20-35 

influence  of  milk  on  yield  of 20-35 

loss  of  fat  in  ripening  of 41 

loss  of  water  in  ripening  of,  41,  45,  55,  58-59,  66,  69, 

78-79,  90-92,  102,  105 
loss  in  weight  in  ripening  of  (see  Loss  of  water). 

losses  in  making  of 6,  10,  18,  20-35,  64,  93 

made  from  milk  containing  added  cream, 

6,  10,  17,  20-25 

made  from  normal  milk  rich  in  fat 26 

made  from  skimmed  milk 20-25 

market  value  increased  by  cold  storage  (see  Cold 
storage). 

market  value  of  casein  and  water  in 32,  67 

milk  required  to  make  one  pound  of,  20-35,  66,  93-100 

paraffining  of 10,  45-46,  55,  58-59,  63,  79,  91 

print    76 

production  comparison  of  dairy  breeds 34 

quality  improved  by  cold  storage  (see  Cheese,  cold 
cured). 

quick  ripening,  conditions  for 46 

rise  and  fall  of  bacteria  in 68 

sage 10 

slow-ripening 46 

solids  in 20-33 

soluble  proteins  in 40,  43-46,  74-75,  77 

sources  of  carbon  dioxid  in 43 


470     SCIENCE   AND    PRACTICE    OF    CHEESE-MAKING 

Cheese — continued 

stirred-curd,  comparison  with  cheddar  process, 

10,  20.-25 
texture,  relation  of,  to  conditions  of  ripening, 

39,  45-46,  55,  58-59,  76-80,  90-92,  102,  105 

varieties  of,  descriptions  and  analyses 60 

water  in 20-3  5 

yield  and  milk-fat 20-35,  66,  93 

Cheese-curd  (see  Curd). 

Cheese-factories,  methods  of  paying  for  milk  at, 

32,  64,  67,  90-92,  93 

Cheese-making,  albumin  lost  in 20-35 

•  casein  lost  in 20-3  5 

cheddar  process  of 20-3  5 

effect  of  adding  cream 20-25 

effect  of  adding  skim-milk 20-25 

effect  of  cutting  curd  hard  and  soft ....  20-35 
effect  of  exposing  milk  to  foul  odors ....  24 

effect  of  shutting  up  milk  in  cans 24 

effect  of  tainted  milk 23,  24,  73 

effect  of  using  different  amounts  of  rennet, 

20-25 

experiments  in 6,  18,  20-25,  90-100 

fat  lost  in,  6,  18,  20-25,  64,  66,  67,  90,  92, 

93-100 

pure  lactic  acid  cultures  in 68 

Cheese-ripening,  effect  of  moisture 10,  41,  45,  68 

effect  of  rennet 26,  44,  75,  77 

effect  of  salt 46,  66 

effect  of  size 41,  46 

effect  of  temperature,  8,  10,  41,  45-46,  55, 

58-59,  69,  76-80,  90-92,  102,  105 

use  of  hygrometer  in 27,  68 

Chemical  changes  in  cheese 46 

composition  of  cheese 20-25,  45-46 

composition  of  milk 20-25 

composition  of  whey 20-25 

Chloroformed  cheese  (see  Cheese,  chloroformed). 
Cold-cured  cheese  (see  Cheese,  cold-cured). 
Composition  of  cheese,  milk  and  whey  (see  Chemical  com- 
position). 
Cream,  addition  to  normal  milk  in  cheese-making, 

6,  10,  17,  20-25 
Curd,  comparison  of  ordinary  and  high  temperatures  of 

heating 20-25 

cutting  of 20-35 

effects  of  cutting  coarse  and  fine 20-25 


INDEX    TO    LITERATURE    OF    CHEESE-MAKING      471 

Curd — continued 

effects  of  cutting  hard  and  soft 20-25 

gassy 3,  10,  15,  67,  108 

heating  and  stirring 20-35 

temperature  used  in  heating 20-35 

time  from  cutting  to  drawing  whey 20-35 

Curd-test  for  detection  of  tainted  milk 73 

Curing-rooms 27,  41,  45-46,  68,  78 

moisture  supply  in 27,  41,  68 

Dairy,  statistics  of 52 

cows,  records  of 75 

schools 54 

Drouth,  effects  of,  on  milk  and  cheese  production 36 

Edam  cheese,  manufacture  and  composition  of 19,  27 

Enzyms,  action  in  cheese 40,  44,  74,  75 

effect  of  chloroform,  ether  and  formalin  on, 

40,  50,  73 

effect  of  acids  on 40,  44,  73 

effect  of  heat  on 40,  73 

effect  of  salt  on 40,  73 

galactase 40,  69,  73,  74 

in  milk 40,  69,  73 

in  rennet 40,  44,  75,  77 

Ether,  effect  of,  on  the  action  of  enzyms 40,  74 

Factories  (see  Cheese-factories). 

Fat,  amount  in  cheese 20-35 

amount  in  milk 20-35 

amount  in  whey 20-3  5 

amount  lost  and  recovered  in  cheese-making 20-35 

in  cheese,  influence  on  ripening  of  cheese 41,  46 

in  milk,  relation  of,  to  casein  in  cheese 20-35 

in  milk,  relation  of,  to  fat  in  cheese 20-35 

in  milk,  relation  of,  to  composition  of  cheese 20-35 

in  milk,  relation  of,  to  yield  of  cheese 20-35 

in  milk,  relation  to  casein  in  milk 20-35 

in  milk,  relation  to  casein  in  skim -milk 20-25 

in  milk,  yield  of  cheese  for  each  pound  of 20-35 

Feeding  value  of  whey 65 

Flavor  of  cheese 20-25 

bitter,  in  cheese  and  milk 46,  101 

relation  of  bacteria  to  cheddar  cheese 36,  67,  102 

relation  of  conditions  of  ripening  to,  39,  45-46,  55, 

58-59,  76-78,  90-92,  102,  105 

relation  of  yeasts  to,  in  cheese 83,  108 

sweet,  in  cheese 38 

tainted,  in  milk  and  cheese 23-25,  72 

Foods  affecting  flavor  of  cheese 20-25,  81 


472     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


Gas-producing  bacteria  in  curd  and  cheese.  .3,  10,  15,  67,  108 

Gouda  cheese,  manufacture  and  composition  of 19,  27 

Hot -iron  test 67 

Lactation  advancing,  influence  on  casein  and  albumin  in 

milk 20-35 

influence  on  cheese  production.  .  .20-35 

influence  on  fat  in  milk 20-35 

influence  on  ratio  of  fat  to  casein,  20-35 

Lactic  acid,  action  on  casein 48 

development  of,  in  cheese-making 61 

pure  cultures  in  cheese-making 68 

Loss  of  casein  in  cheese-making 20-25 

carbon  dioxid  in  cheese-ripening 43 

fat  in  cheese -ripening 6,  10,  18,  20-35,  64,  93 

milk  constituents  in  cheese-making,  6,  10,  18, 

20-35,  64,  93 

solids  in  cheese-ripening 26,  41 

water  in  cheese-ripening,  41,  45,  55,  58-59,  66,  69, 

78-79,  90-92,  102,  105 

weight  in  cheese-ripening  (see  Loss  of  water). 
Manufacture  of  cheese  (see  Cheese-making). 

Metals  and  rennet  action 86 

Milk,  absorbed  odors  in 38,73 

aeration  of 9,  16,  24,  25,  66 

albumin  in 20-3  5 

amount  required  for  cheese 20-35,  66,  93 

analyses  of  (see  Analyses). 

at  cheese -factories,  methods  of  paying  for  (see 
Cheese-factories) . 

average  composition  of 20-35 

care  and  handling  of 5,16 

casein  in  (see  Casein). 

cheese-producing  constituents  of 20-35 

coagulation  by  rennet 20-35 

composition  of 20-35 

composition  of,  relation  to  composition  of  cheese .  .  20-35 
constituents  lost  in  cheese-making  (see  Loss  in  cheese- 
making)  . 
containing  added  cream,  relation  of  fat  to  casein  in, 

20-25 

effect  of  exposing  foul  odors  on  cheese-making 24 

effect  of  shutting  up  in  cans 24 

enzyms  (see  Enzyms  in  milk), 
fat  in  (see  Milk-fat). 

fermentation  of  sugar  in 76 

flavors  in 3,  10,  15,  20-25,  39,  67,  81,  108 


INDEX    TO    LITERATURE    OF   CHEESE-MAKING      473 

"Milk— -continued 

influence  of  composition  of,  on  composition  of  cheese, 

20-35 
paying  for,  in  cheese-making  (see  Cheese-factories). 

relation  of  albumin  and  casein  in. 20-35 

relation  of  casein  and  fat  in 20-35 

required  to  make  one  pound  of  cheese.  .  .  .20-35,  66,  93 

ripening  before  setting 67 

skimmed,  relation  of  fat  to  casein  in 20-25 

solids   in 20-3  5 

sour,  handling  of,  in  cheese-making 73 

sugar  in 20-35 

tainted 3,  10,  15,  20-25,  67,  72,  108 

Milks,  difference  in  cheese-producing  power  of  different, 

20-35,  71 

effect  of  adding  cream  to,  in  cheese-making 20-25 

effect  of  adding  skim-milk  to,  in  cheese-making.  .  20-25 
effect  of  removing  fat  from,  in  cheese-making  .  .  .20-25 

Milk -cans,  rusty  and  rennet  action 87 

Milk-fat,  and  cheese  yield 20-35,  66,  93 

as  a  basis  for  measuring  cheese  yield,  20-35,  66,  93 
as  a  basis  of  paying  for  milk  at  cheese-factories 
(see  Cheese-factories). 

cheese  from  normal  milk  rich  in 26 

cheese-producing  power  of 20-35 

effect  of  drouth  on 36 

influence  on  composition  of  cheese 20-35 

influence  on  yield  of  cheese 20-35 

loss  of,  in  cheese-making  (see  Loss  of  fat). 

relation  to  casein  in  milk 20-35 

relation  to  casein  in  skimmed  milks 20-25 

yield  of  cheese  for  each  pound  of 20-25,  66,  93 

Milk-solids  and  cheese  yield 20-35,  66 

cheese-producing 20-35 

in  whey 20-35 

relation,  specific  gravity  to 67 

New  York  State,  cheese  industry  of 53 

Nitrogen  compounds  in  cheese  .  .  .  .20-35,  40,  43-46,  49,  74-75 

in  milk 20-35 

water-soluble  in  cheese,  20-35,  40, 

43-46,  49,  74-75 

Paracasein  in  cheese 20-35,  40,  43-46,  49 

Paraffin,  effect  of  use  on  cheese,  10,  45-46,  55,  58-59,  63,  79,  91 
Paraffining,  effect  on  market  value  of  cheese,  45,  55,  58-59, 

Pepsin,  commercial,  action  in  cheese-ripening 44,  75 


474     SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 

Phosphates,  acid  in  cheese 49 

soluble  in  cheese 49 

Products  in  cheese-ripening,  cumulative  and  transient ....  46 
Quality  of  cheese  improved  by  cold  storage  (see  Cheese, 
cold-cured). 

of  cheese,  influence  of  fat  on 6,  17,  20-25,  66 

Rennet,  action  in  cheese-ripening 26,  44,  46,  75,  77 

effect  of  metals  on 86 

effect  of  rusty  cans  on 87 

effect  of  salt  on 73 

effect  of  varying  strength  of,  in  coagulating 

milk   73 

effect  of  watered  milk  on 73 

Rennet -extratet,  amount  used  in  cheese-making 20-35 

comparison  of  commercial  and  home- 
made   20 

comparison  of  commercial  and  pepsin ....  44 
relation  to  cheese-ripening. 26,  44,  46,  75,  77 
Ripening  of  cheese  (see  Cheese-ripening). 

Ripening  milk  before  setting 67 

Room,  curing  for  cheese  (see  Curing-rooms). 

Rusty  spots  in  cheese 38,  42 

Sage  cheese 10 

Salt,  effect  on  action  of  rennet  in  cheese-ripening  .  .40,  44,  46 
effect  on  action  of  enzyms  in  cheese-ripening,  40,  44,  46 

effect  on  moisture  in  cheese 46,  66 

effect  on  quality  of  cheese 46,  66 

brine,  cheese  protein  soluble  in 40,  44-46 

Schools,  dairy 54 

Separator,  centrifugal,  cleaning  milk  with 24,  66 

removing  casein  from  milk  with.  .  .67 

Skim-milk,  effect  of  use  in  cheese-making 20-25,  37 

relation  of  fat  to  casein  in 20-25,  37 

ripening  of  cheese  made  from 46 

Solids  in  cheese 20-35,  67 

in  milk 20-35,  67 

in    whey 20-35,  67 

Sour  milk,  making  cheese  from 73 

Souring  of  milk,  associative  action  of  bacteria  in 11-14 

Specific  gravity,  relation  of  milk-solids  to .67 

Spots,  rusty,  in  cheese 38,  42 

Starter,  use  in  cheese-making 20-25,  68 

Statistics  of  the  dairy 52 

Stirfed-curd  and  cheddar  processes,  comparison  of,  10,  20-25 

Sugar  in  cheese 20-35,  49 

in  milk 20-35 

in  whey 20-35 

Sweet  flavor  in  cheese .  .  38 


INDEX    TO    LITERATURE    OF    CHEESE-MAKING      475 

Swiss  cheese,  manufacture  of 82 

yeast  fermentation  in 82,  83,  85 

Taints  in  milk  and  cheese  (see  Cheese  and  milk). 

Temperature  in  cheese-making 20-35 

in  cheese-ripening  (see  Cheese-ripening). 

Texture  of  cheese,  influence  of  acid  on 67 

relation  to  conditions  of  ripening, 
39,  45-46,  55,  58-59,  76-80,  90-92,  102,  105 

Udder,  bacteria  in  and  enzyms  in  milk 4,  40 

Varieties  of  cheese,  descriptions  and  analyses  of 60 

Water  in  cheese 20-35 

effect  on  commercial  quality,  41,  45-46, 

55,  58-59,  79 

market  value  of 45-46 

value  to  consumers  and  dairymen 46 

in  milk 20-35 

in  whey 20-35 

Weight  lost  by  cheese  in  ripening,  41 .  45,  55,  58-59,  66,  69, 

78-79,  90-92,  102,  105 

Whey,  albumin  in 20-35 

analyses  of 20-35 

butter 2,132 

casein  in 20-35 

composition  of 20-35 

feeding  value  of 65 

solids  in 20-35 

Wisconsin,  cheese  industry  of 70 

Yeasts  in  cheese-making,  troubles  from 82,  83,  85 

Yield  of  cheese  and  composition  of  milk 20-35 


Index 


Page 

Absorption  of  flavors  by  milk.  ..        6 
Absorption    of    flavors    by   milk 

from  foods 7 

Acid  body,  cause,  prevention,  etc. 

of 122 

Acid  calcium  phosphate  in  cheese- 
ripening 358 

Acid  flavor  in  cheese,  cause,  pre- 
vention, etc 116 

Too  little 82 

Too  much 82 

Acid,    lactic,    action    in    cheese- 
ripening.  356 

Fermentation 292 

Abnormal 295 

From  milk-sugar 149 

Acid  salts,  effect  on  rennet  action  308 

In  cheese-ripening 334 

Acid  test,  Mann's 428 

Acid-cut  color 89,  129 

Acidity  and  body  of  cheese 52 

Color  of  cheese ~  •  52 

Contraction  of  curd 51 

Expulsion  of  whey 52 

Finish  of  cheese 53 

Flavor  of  cheese 52 

Keeping  quality  of  cheese.  ...      53 

Rennet  action 51 

Texture  of  cheese 52 

In  cheese,  excessive,  causes  of.  51 
Cheese-making,  control  of.  ...  53 
In  curd  and  cheese,  effects  of .  .  45 
In  curd  and  cheese,  conditions 

of 45 

Insufficient,  cause  of 50 

Of  cheese,  excessive,  causes  of     50 

Of  milk 152 

Of  milk  in  ripening 21 

Of  milk,  quick  test  for.  ......    429 

Of  whey  from  curd   at  salting.     37 

Of  whey  in  heating  curd 30 

Of  whey  when    cheddaring  is 

complete 35 

Of  whey  when  drawn  from  curd     3 1 

Of  whey,  testing 429 

Relation  of,  to  moisture,  in  curd     47 

Test 426 

Test  for  ripening  milk.  .......      21 

Acids,  action  on  casein 143 

Effect  on  rennet  action 306 

In  cheese-ripening,  action  of .  .  356 
Use  of,  in  cheese-making 63 


Page 

Aeration  of  milk 12 

Albumin  in  milk  and  cheese-mak- 
ing     139 

Relation  to  casein 172 

Alkaline   salts,   effect  on   rennet 

action 308 

Alkaline  tablet  test,  Farrington's  428 

Alkalis,  action  on  casein 145 

Effect  on  rennet  action 308 

American  cheddar  cheese,  sizes  of     44 

Amino  acids  in  cheese 331 

Ammonia  in  cheese 331 

Appearance  of  cheese,  definition 

9f 90 

Architecture  of  cheese- factories .  .      98 

Ash  of  milk 150 

Ayrshire    milk,    composition    of 

cheese  from 232 

Babcock  test  for  fat  in  milk 423 

Bacillus  lactici  acidi 292 

Bacteria,  action  in  cheese-ripening  371 
Action  of  sunlight,  chemicals, 

etc 289 

Ball-shaped 287 

Changes  produced  by.  .......    289 

Corkscrew-shaped 287 

Description  of 287 

Digesting 295 

Distribution  of 281 

Effect  of  temperature 288 

Food  requirements  of 288 

Gas-producing 295 

Growth  and  reproduction 287 

Kinds  of 287 

Producing  bad  flavors 296 

Rod-shaped 287 

Bacterial      infection      of    milk, 

sources  of 4 

Bitter  flavor 83 

Body,  acid,  cause,  remedy,  etc. ,  of   122 

Cause,  etc.,  of  defects  in 121 

Corky 87 

Crumbly 88 

Curdy 87 

Dry,  cause,  remedy,  etc 121 

Firm 87 

Gritty 88 

Mealy 88 

Meaty 87 

Of  cheese  and   acidity 52 

Of  cheese,  definition  of 86 

Of  cheese ,  effect  of  moisture  on     47 

477 


478        SCIENCE    AND    PRACTICE    OF     CHEESE-MAKING 


Page 

Body  of  cheese,  testing 87 

Overdry 88 

Pasty 87 

Perfect 87 

Salvy 87 

Silky 87 

Smooth 87 

Solid 87 

Stiff 87 

Watery 88 

Waxy 87 

Weak 87 

Borax,  effect  on  rennet  action .  .  .    308 

Boxes,  cheese,    stenciling 77 

Boxing  cheese  for  shipment 77 

Brands  on  cheese,  use  of 72 

Breed,   influence   of,  on   fat  and 

casein 165 

Breeds  of  cows,  casein  and  albu- 
min in  milk  of 173 

Brine-soluble  protein  in  cheese- 
ripening 359 

Brine-soluble  substance  from 

casein 147 

Butter  and  cheese,  making  of . .  .      69 
Butter-fat  (see  Milk-fat). 
Butter,  whey,  manufacture  of . .  .      65 
Calcium  phosphate,  insoluble,  in 

cheese-ripening 358 

Soluble  in  cheese-ripening 358 

Calcium    salts,    action    on   para- 
casein     304 

Effect  on  rennet  action 306 

In  milk,  action  of  rennet  on ...    304 
Calculating  cheese  yield,  accuracy 

of  methods 226 

Cheese  yield  from  fat 213,  224 

Cheese  yield  from  fat  and  casein 

216,  225 

Cheese  yield  for  different  per- 
centages of  water 224 

Dividends  at  cheese-factories.  .   279 

Milk-solids 438 

Per  cent  of  casein  in  milk 170 

Yield  of  green  cheese 211 

Yield  of  ripe  cheese 225 

Care  of  cheese 71 

Of  milk  at  factory 17 

Of  milk  at  farm 3 

Casein,  action  of  acids  on 143 

Action  of  alkalis  on 145 

Action  of  enzyms  on 147 

Action  of  heat  on 146 

Action  of  rennet  on 1 46 

Action  of  salts  on . 146 

Amount  of,  in  milk 161 

And  albumin,    relations  of,  in 

milk 172 

And  fat,  average  in  factory  milk  172 
And    fat,     calculating     cheese 

yield  from 216,  220 

And  fat  in  milk,  relation  of 164 


Page 
Casein   and   fat,  paying   for  milk 

on   basis  of 269 

And  fat,  relati9n  to  cheese  yield  187 
And  fat,  relation  of,  in  factory 

milk 167,  169 

And  paracasein,  relation  of. ...    305 

And  stage  of  lactation 162 

Brine-soluble  substance  from.  147 
Calculated,  and  fat,  paying  for 

milk  on  basis  of 276 

Calculating  amount  of,  in  milk  170 
Change  of,  into  paracasein ....  303 

Composition  of 141 

Differing  from   paracasein ....    303 

Digestion  by  rennet 306 

Functions  of,  in  cheese 178 

In  cheese-factory  milk 163 

In  milk,  effect  of  drouth  on.  .  .  163 
In  milk,  effect  of  pasturage  on  163 

In  milk,  insoluble 142 

In  milk  of  different  breeds  of 

cows 161 

Loss  of,  in  cheese-making 194 

Test  for 440 

Caseoses  in  cheese 330 

Central  curing-station 394 

Cheddar  cheese,  American,  sizes  of     44 

Defects  in 113 

From  pasteurized  milk 60 

Cheddaring  curd,  operations  of .  .      32 

Cheddaring  operation,  objects  of     34 

Operation,  when  complete.  ...      35 

Texture  produced  by 35 

Velvety  appearance  of  curd  in     35 

Cheese,  acid  flavor  in 1 16 

Acidity  and  finish  of 53 

Acidity  and  keeping-quality  of  53 
American  cheddar,  sizes  of.  ...  44 

Amino  acids  in 331 

Ammonia  in 331 

And  butter,  making  of 69 

And  whey,  distribution  of  milk 

constituents  in 203 

Body  of,  and  acidity 52 

Boxing  for  shipment 77 

Calculating  yield  of 211 

Care  of 71 

Caseoses  in 330 

Causes  of  excessive  acidity  in .  .  50 
Causes  of  excessive  moisture  in  46 
Causes  of  insufficient  acidity  in  50 
Changes  in  fat  of,  in  ripening.  .  331 

Cheddar,  defects  in 113 

Club,  making  of 405 

Commercial   qualities  of 80 

Composition,     effect    of    skim- 
ming milk  on 234 

Composition  of,  and  milk  con- 
stituents     231 

Composition  of,  and  quality.  .  .    243 

Conditions  of  acidity  of 45 

Conditions  of  moisture  in.  ...  45 
Color  of,  and  acidity 52 


INDEX 


479 


Cheese,  cottage,    composition  of    40* 

Cottage,  making  of 400 

Covering  with  paraffin 74 

Cracked  rinds  in 133 

Creani,   making  of 405 

Defects  in  flavor  of 115 

Definition  of  body  of 86 

Definition  of  flavor  of 84 

Definition  of  texture  of 84 

Drawing  to  shipping  point.  ...      78 

Dressing  of 43 

Edam,  making  of 406 

Effect  of  freezing  on  quality  of  390 
Effect  of  paraffining  on  loss  of 

weight  of 319 

Effects  and  control  of  moisture 

in 45 

English  sage,  making  of 399 

Excessive  acidity  in,  cause  of .  .      50 

Finish  in 91 

Flavor  of,  and  acidity 52 

Flavors,  causes  of 375 

Food  flavors  in 119 

From  Ayrshire  milk,  composi- 
tion of 232 

From  Guernsey  milk,  composi- 
tion of 232 

From  Holstein  milk,  composi- 
tion of 232 

From  Jersey  milk,  composition 

of........ 232 

From  normal  milk,  composition 

of. 231 

From  pasteurized  milk 60 

From  rich  milk,  composition  of  237 
From  skimmed  milk,  composi- 
tion of 233 

Functions  of  casein  in 179 

Functions  of  fat  in 177 

Functions  of  water  in 180 

Gas-holes  in 86 

Gassy,  green  fodder  a  source  of       7 

Gouda,  making  of 415 

Home-trade 62 

How  to  sell 78 

Immediate   removal  from  fac- 
tory     393 

Judging  commercial  qualities  of 

80,  91 

Mechanical  holes  in 86 

Methods  of  grading ' 

Methods  of  scoring 93 

Milk  constituents  and  yield  of  186 
Milk-sugar,      changes     of,     in 

ripening 333 

Moisture    in,    effects  on   weight 

lost  in  ripening 323 

Moisture  in,  right  amount 382 

Moldy,  cause,  etc 134 

Neuf  hatel,  making  of 404 

Off  flavors  in 116 

Paranuclein  in 330 


Page 

Cheese,  paying  for 79 

Peptones  in 330 

Placing  in  curing-room 71 

Poison 68 

Profits  from  proper  ripening  of  39 1 
Proteins  in,  agents  changing.  .  355 
Quality  of,  in  rel  tion  to  mois- 
ture   381 

Quick-ripening 60 

Red  spo\s  in 89 

Ripe,  calculating  yield  of.  .  .225 

Sale  of 71 

Sampling  of 80 

Shipment  of 71,  73 

Size  of,  effect  of  weight  lost  in 

ripening 320 

Skim-milk 250 

Slow  ripening 60 

Standards  of  states ' 241 

Standard  of  United  States. ...  237 

Stilton,  making  of 398 

Testing 80 

Testing  body  of 87 

Testing  color  of 88 

Testing  flavor  of 81 

Testing  texture  of 84 

Texture  of,  and  acidity 52 

Texture  of,  effect  on  loss  of 

moisture 324 

Turning  of 72 

Unclean  surface  of,  remedy. .  .  133 

Uncplored 89 

Unripe,  acid  salts  in 328 

Unripe,  chemical  compounds  in  327 

Unripe,  milk-sugar  in 328 

Unripe,  neutral  salts  in 328 

Unripe,  proteins  in 328 

Unripe,  salt  in 329 

Water  in,  value  to  consumers.  .  383 
Water  in,  value  to  dairymen .  .  380 

Weighing  for  shipment 76 

White  specks  in 88,  332 

With  different  percentages  of 

water,  calculating  yield  of .  .  224 
Yeasty,  cause,  prevention,  etc.  126 
Yield,  accuracy  of  methods  of 

calculating 226 

Yield  and  solids,  paying  for 

milk  on  basis  of 261 

Yield,  calculating  from  fat,  213,  225 
Yield,  calculating  from  fat  and 

casein 216,  220 

Yield,  factors  of 186 

Yield  of,  effect  of  skimming 

milk  on 234 

Yield  of,  effect  of  starters  on .  .  69 
Yiefd,  relation  of  fat  and  casein 

to 187 

Yield,  relation  of  milk-fat  to.  .    204 

Yield,  relation  of  water  to.  ...    198 

Cheese-box,  proper  appearance  of     78 

Cheese-boxes,  stenciling 77 


480        SCIENCE    AND    PRACTICE    OF     CHEESE-MAKING 


Page 

Cheese-brands,  use  of 72 

Cheese-factories,  calculating  divi- 
dends at 279 

Paying  for  milk  at 253 

Cheese-factory  architecture 98 

Association 453 

Co-operation 452 

Construction 97 

Curing-room  in 102,  394 

Drainage 99 

Equipment 106 

Furnishings 106 

Losses  in  ripening 379 

Management 451 

Method  of  disinfecting 132 

Milk,  casein  in 163 

Milk,  composition  of 175 

Milk,  fat, in 159 

Milk,  relation  of  fat  and  casein   169 
Milk,  variations  in  composition 

of. 176 

Organization 451 

Plans  of  construction 105 

Water  supply  of 99 

Cheese-making  and  micro-organ- 
isms     285 

Care  of  milk  for 3 

Clean  milk  for 3 

Colostrum  milk  in 12 

Control  of  acidity  in 53 

Control  of  moisture  in 48 

First  steps  in 15 

Functions  of  casein  in 178 

Functions  of  milk  constituents 

in 177 

Functions  of  milk-sugar  in ....    182 
Functions  of  salts  of  milk  in.  .    184 

Granular  process  of 55 

Judging  milk  for 12 

Loss  of  casein  in 194 

Loss  of  milk-fat  in 188 

Loss  of  milk  constituents  in.  .  .    188 

Paying  for  milk  for 253 

Relation  of  enzyms  to 285 

Ripening  milk  for 18 

Science  of 137 

Soaked-curd  process  of 57 

Stirred-curd  process  of 55 

System  of  records  for 16 

Use  of  acids  in 63 

Use  of  pepsin  in 64,  312 

Use  of  starter  in 21 

Cheese-producing  solids  in  milk.  .    200 

Cheese-ripening 313,  327,  354,  379 

Acid  salts  in 334 

Action  of  acids  in 356 

Action  of  bacteria  in 371 

Action  of  galactase  in 368 

Action  of  pepsin  in 365 

Action  of  rennet  on 346,  361 

Causes  of  chemical  changes  of,  354 
Chemical  changes  in 327 


Page 

Cheese-ripening,  changes  in 314 

Changes  in  proteins  in 330 

Chemical,  definition  of ."37 

Conditions  affecting  quality 

324,  388 

Cumulative  products  in 350 

Effect  of  moisture  on  chemistry 

of 340 

Effect    of   moisture    of   air   on 

weight  lost  in 317 

Effect  of  paraffin  coating  on 

319,  389 

Effect  of  salt  on 343 

Effect  of  size 3-42 

Effect  of  size  on  weight  lost  in 

320,  387 
Effect  of  temperature  on  loss  of 

weight  in 315 

Effect      of      temperature      on 

quality 324,  388 

Effect    of    time    on    chemical 

changes  of 337 

Factory  losses  in 379 

Gases  in 334 

Influence  of  products  on 351 

Loss  of  weight  in 314 

Measuring  rate  of 336 

Milk-sugar  in 357 

Neutral  salts  in 334 

Proper  conditions 394 

Temperature  and  weight  lost.  .  386 

Transient  products  in 350 

Why  moisture  affects 353 

Cheese-scoring   cards 94 

Chemical  changes  in  cheese-ripen- 
ing  327 

Of  cheese-ripening,  causes  of .  .  354 
Of    cheese-ripening,     effect    of 

temperature  on 338 

Of    cheese-ripening,    effect    of 

time  on 337 

Chemical    compounds    in    unripe 

cheese 327 

Chemical     products     of     cheese- 
ripening,  effect  on  process.  .  351 
Chloroform,      effect     on     rennet 

action 308 

Chymosin  of  rennet 299 

Clean  flavor 82 

Milk  for  cheese-making 3 

Milk,  how  to  obtain 8 

Cleaning  and  disinfecting,  method 

of 132 

Close  texture 86 

Coagulating  action  of  rennet,  ex- 
planation   of 302 

Coagulation  by  rennet,  imperfect, 

causes  of 23 

Of  milk,  effect  of  temperature  309 

Color,  acid-cut,  cause,  etc 89,  129 

Defects  in,  cause,  etc 129 

High 89 


INDEX 


Color,  light 89 

Mottled,  cause,  etc 89,  129 

Of  cheese  and  acidity 52 

Of  cheese,  testing  of 88 

Pale,  cause,  remedy,  etc 129 

Perfect 88 

Rusty-spot,  cause,  etc 131 

Seamy,  cause,  etc 89,  130 

Straight 88 

Streaked 89 

Translucent 88 

Wavy 89 

Coloring-matter,  adding  to  milk.  22 
Colostrum  milk  in  cheese-making  12 
Commercial  qualities  of  cheese ...  80 

Score-cards 94 

Starter 19  . 

Composition  of  cheese  and  milk 

constituents 231 

Of  cheese  and  quality 243 

Of  cheese,    effect  of  skimming 

milk  on 234 

Of  cheese-factory  milk 175 

Of  cheese  from  Ayrshire  milk.  .  232 
Of  cheese  from  Guernsey  milk  232 
Of  cheese  from  Holstein  milk. .  232 
Of  cheese  from  Jersey  milk.  .  .  232 
Of  cheese  from  normal  milk.  .  .  231 

Of  cheese  from  rich  milk 237 

Of  cheese  from  skimmed  milk.    233 

Of  cottage-cheese 404 

Of  milk,  diagram  showing.  ...    195 

Of  whey.... 195 

Constituents  of  milk 139 

Of  milk,  conditions  affecting.  .    155 
Construction  of  cheese-factory. . .      97 

Of  curing-room 102 

Corky  body 87 

Cottage-cheese,  composition  of.  .    404 

Making  of 400 

Qualities  of 403 

Yield  of 403 

Cows,  fat  in  milk  of  breeds 157 

Cowy  flavor 83 

Cracked  rinds,  cause,  etc 133 

Cream  cheese,  making  of ........    405 

Crumbly  body 88 

Cubes  of  curd 26 

Curd,  acidity  of  whey  when  drawn 

from 31 

Amount  of  salt  to  use  on 38 

Behavior  after  cutting 27 

Cheddaring,  operations  of 32 

Conditions  of  acidity  of 45 

Conditions  of  moisture  in 45 

Contraction  of,   and  acidity.  .  .      51 

Cubes  of 26 

Effects  and  control  of  acidity  in     45 
Effects  of  cutting  fine  or  coarse     27 
Effects  of  pressing  at  low  tem- 
peratures        41 


Curd,  effects  of  pressing  at  high 

temperatures 41 

Film  on 29 

Firming  of 29 

Heating 29 

How  high  to  heat 29 

How  to  apply  salt  to 39 

How  to  cut 26 

How  to  press 42 

Length  of  strings  on  hot  iron,  at 

salting     37 

Matting  of 32 

Milling    objects  of 35 

Piling  of 32 

Preparation  of  hoop  for 42 

Pressing 40 

Pressing,  objects  of. 41 

Pressing  of,  regulation  of 42 

Purpose  of  cutting 25 

Regulation  of  heating 30 

Removal  of  whey  from 31 

Rule  for  heating 30 

Salting 37 

Salting,  effects 39 

Stirring  after  cutting 28 

Stirring  to  dry 32 

Stringing  of,  on  hot  iron.  .31,  35,  37 
Temperature  of,  at  pressing.  .  .  40 
Texture  of,  produced  by  ched- 

daring 35 

Velvety    appearance    in    ched- 

daring 35 

When  to  cut 25 

When  to  heat 29 

When  to  mill 35 

When  to  press 40 

When  to  remove  whey  from ...      31 

When  to  salt 37 

Curd-test,  Wisconsin 435 

Curdy  body 87 

Curing-room  at  cheese-factory.  .  .    394 

Construction  of 102 

Effect  of  moisture  in,  on  weight 

lost 317 

Placing  cheese  in 71 

Curing-stations,  central 394 

Cutting  curd  fine  or  coarse,  effect 

of 27 

Curd,  rules  for 25 

Stirring  curd  after 28 

Daisies,  size  of 44 

Defects  in  body,   cause,  preven- 
tion, etc 121 

In  cheddar  cheese 113 

Color,  cause,  etc 129 

In  finish,  cause,  etc 129 

In  flavor 115 

Digesting  action  of  rennet 306 

Bacteria 295 

Dirt  in  milk,  tests  for 433 

Disinfecting,  method  of 132 

Dissolving  action  of  rennet 306 


482        SCIENCE    AND    PRACTICE    OF     CHEESE-MAKING 


Page 
Dividends,      calculation     of,     at 

cheese- factories 279 

Drainage  of  cheese-factory 99 

Dressing  of  cheese .....' 43 

Drouth,  effect  upon  relation  of  fat 

and  casein 168 

Effect  on  milk-casein 163 

Dry  body,  cause,  remedy,  etc.,  of  121 

Drying  curd  by  stirring 32 

Edam  cheese,  making  of 406 

Educational  score-cards 94 

English  sage  cheese,  making  of  .  .    399 

Enzym,  pepsin 312 

Rennet,  conditions  of  action.  .    306 
Rennet,  digesting  action  of . .  .    306 

Enzyms,  action  on  casein 147 

And  cheese-making 285,  291 

In  milk 297 

Of  milk 153 

Equipment  of  cheese-factory.  ...    106 
Export  cheddar  cheese,  size  of . . .      44 

Factors  of  cheese  yield 186 

Factory  architecture 98 

Construction  and  material  for,  97,  98 

Drainage 99 

Equipment 106 

First  care  of  milk  at 17 

Location  of 97 

Method  of  disinfecting 132 

Milk,  fat  and  casein  in 172 

Plans  of  construction 105 

Site  of 97 

Water-supply  of 99 

Farrington's  alkaline  tablet  test.    428 

Fat,  amount  of,  in  milk 156 

And  calculated   casein,  paying 

for  milk  on  basis  of 276 

And  casein  average  in  factory 

milk.... 172 

And  casein,  calculating  cheese 

yield  from 216,  220 

And   casein,    effect   of   drouth 

upon  relation  of 168 

And  casein  in  milk,  influence  of 

breed  on 165 

And  casein  in  milk,  relation  of  164 
And  casein,  influence  of  lacta- 
tion on  relation  of 166 

And  casein,  paying  for  milk  on 

basis  of 269 

And  casein,  relation  of,  in  fac- 
tory milk 169 

And  casein,  relation  to  cheese 

yield 187 

Calculating  cheese  yield  from 

213,224 

Functions  of,  in  cheese 177 

In  cheese,  changes  in  ripening  331 

In  cheese-factory  milk 159 

In  milk 140 

In  milk,  Babcock  test  for 423 

In  milk,  effect  of  pasturage  on   160 


Page 

Fat,  in  milk,  influenced  by  lacta- 
tion        j5g 

In  milk,  losses  in  cheese-making   188 
In  milk,  relation  to  cheese  yield  204 

In  whey 190,  197 

Lost  in   cheese-making,   condi- 

tions  favoring 192 

Paying  for  milk  on  basis  of . . .   258 
Plus  2   method    of  paying   for 

milk 264 

Globules  in  milk 140 

Fermentation,  definition  of 285 

Lactic  acid 292 

Lactic  acid,  abnormal 295 

Test 435 

Ferments,  characteristics  of 286 

Chemical 286.  291 

Definition  of 285 

Organized 286 

Unorganized 286,  291 

Film  on  curd 29 

Finish  and  acidity  of  cheese 53 

Defects  in,  cause,  etc 129 

In  cheese 91 

Of  cheese,  effects  of  moisture  on     48 

Firm  body : .  .  .      87 

Firming  curd 29 

First  steps  in  cheese-making.  ...      15 
Fish-eye  texture,  cause,  remedy, 

etc 126 

Fishy  flavor 83 

Flat  flavor 82 

Flats,  size  of 44 

Flavor,  bitter 83 

Clean 82 

Cowy 83 

Fishy 83 

Flat 82 

Fruity 83,  118 

High 82 

Hydrogen  sulphid 83 

Low 82 

Of  cheese  and  acidity 52 

Of  cheese,  defects  in 115 

Otf  cheese,  definition  of 84 

Of  cheese,  effect  of  moisture  on     48 

Of  cheese,  testing 81 

Perfect 82 

Quick 82 

Rancid S3 

Sour 83 

Stable 83 

Strong .- 82 

Sweet 83 

Tainted 33 

Tallowy 83 

Too  little  acid 82 

Too  much  acid 82 

Weedy 83 

Flavors,  absorption  of,  by  milk.  .        6 

Acid,  in  cheese 116 

Absorption  from  food  by  milk       7 


INDEX 


483 


Page 
Flavors,  bacteria  producing  bad    296 

Pood,  in  cheese 119 

Fruity,  in  cheese 1 18 

Of  cheese,  causes  of 375 

Off,  in  cheese 116 

Pood    flavors    in    cheese,    cause, 

remedy 119 

Foods,  absorption  of  flavors  from, 

by  milk 7 

Formaldehyd,    effect    on    rennet 

action 308 

Freezing  cheese,  effect  on  quality  390 

Fruity  flavor 83,  118 

Functions    of    casein    in    cheese- 
making 178 

Of  milk  constituents  in  cheese- 
making 177 

Of  milk-sugar  in  cheese-making  182 
Of  salts  of  milk  in  cheese-mak- 
ing     184 

Of  water  in  cheese 180 

Galactase 297 

Action  in  cheese-ripening 368 

And  cheese-ripening 368 

Properties  of 298 

Gases  in  cheese -ripening 334 

Gas-holes  in  cheese 86 

Gas-producing  bacteria 295 

Gassy  milk  and  cheese,  green  fod- 
der as  a  source  of 7 

Texture,  cause,  prevention,  etc.  124 

Gouda  cheese,  making  of 415 

Grading  cheese 95 

Granular  process  of  cheese-mak- 
ing       55 

Greasy  texture,  cause,  prevention, 

etc 125 

Green  fodder,  source  of  gassy  milk 

and  cheese 7 

Gritty  body 88 

Guernsey    milk,    composition    of 

cheese  from 232 

Heat,  action  of,  on  casein 146 

Effect  of,  on  rennet 310 

Heating  curd,  rule  for .  . 30 

Curd,  temperature  of 29 

Curd,  when  to  begin 29 

High  color 89 

Flavor 82 

Holstein    milk,     composition     of 

cheese  from 232 

Home-made  rennet-extract 300 

Home-trade  cheese 44,  62 

Hoop,  preparing  to  receive  curd .  .      42 
Hot  iron,  stringmg'of  curd  on 

31,  35,  37 

Hot-iron  test 439 

Hydrogen-sulphid  flavor 83 

Jersey  milk,  composition  of  cheese 

from 232 

Judging  cheese 80,  91 

Cheese,  scale  of  points  for.  ...      92 


Page 

Judging  cheese,  milk  for  cheese- 
making 12 

Keeping   quality   of   cheese   and 

acidity 53 

Of  cheese,  effect  9f  moisture  on  48 

Lactation  and  casein  in  milk 162 

Effect  on  fat  in  milk 158 

Effect  on  relation  of  fat  and 

casein 165 

Lactic    acid,    action    in    cheese- 
ripening 356 

Fermentation 292 

Fermentation,  abnormal 295 

From  milk-sugar 149 

Lactometer,  Quevenne,  use  of.  .  .  438 
Lactose  (see  Milk-sugar). 

Light  color 89 

Location  of  factory 97 

Longhorn  cheese,  size  of 44 

Loose  texture,  cause,  remedy,  etc. 

86,  123 

Loss  of  casein  in  cheese-making. .  194 

Of  fat,  conditions  favoring.  .  .  .  192 

Of  fat  in  cheese-making 190 

Of  moisture,    effect    of    cheese 

texture  on 324 

Of   weight    in    cheese-ripening, 

effect  of  temperature  on. ...  315 
Losses    of    milk    constituents    in 

cheese-making 188 

Low  flavor 82 

Manns'  acid  test 428 

Marschall  test  for  ripening  milk 

21,  430 

Matting  of  curd 32 

Mealy  body 88 

Meaty  body 87 

Mechanical  holes  in  cheese 86 

Metals,  effect  on  rennet  action .  .  309 
Micro-organisms,  action  in  cheese- 
ripening 371 

And  cheese-making 285 

Milk,  absorption  of  flavors  by. .  .  6 

Acidity  of 152 

Acidity  of,  in  ripening 21 

Addition  of  rennet-extract  to.  .  23 

Adding  coloring  matter  to.  ...  22 

Aeration  of 12 

Albumin  and  cheese-making.  .  139 

Ash  of 150 

Albumin,  relation  to  casein.  .  .  172 

At  cheese- factories,  paying  for.  253 
Ayrshire,    composition    of 

cheese  from 232 

Baboock  test  for  fat  in 423 

Care  of,  for  cheese-making.  ...  3 

Bacterial  infection  of,  sources.  4 

Cheese-factory,  composition  of  175 

Cheese-factory,  fat  m. 159 

Clean,  for  cheese-making 3 

Clean,  how  to  obtain 8 

Colostrum  in  cheese-making.  . .  12 


SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


Page 

Milk,  conditions  affecting  con- 
stituents of 155 

Constituents  and  cheese  yield.  186 
Constituents  and  composition 

of  cheese 231 

Constituents,  distribution  in 

whey  and  cheese 203 

Constituents,  functions  of,  in 

cheese-making 177 

Constituents,  losses  of,  in 

cheese-making 188 

Constituents  of 139 

Diagram  showing  composition 

of. 195 

Enzyms  in. .. 153,  297 

Factory,  casein  in 163 

Factory,  relation  of  fat  and 

casein  in 169 

Factory,  variations  in  composi- 
tion of 176 

Finding  degree  of  ripeness  of .  .  21 

First  oare  of,  at  factory 17 

Freshly  drawn,  effect  of  rennet 

on 310 

Gassy,  green  fodders  a  source'of  7 
Guernsey,  composition  of 

cheese  from 232 

Holstein,  composition  of  cheese 

from 232 

Jersey,  composition  of  cheese 

from 232 

Judging  for  cheese-making 12 

Normal,  composition  of  cheese 

from 231 

Pasteurized,  cheese  from ...  60,  404 
Paying  for,  on  basis  of  cheese 

yield  and  solids 261 

Paying  for,  on  basis  of  fat 258 

Paying  for,  on  basis  of  fat  and 

casein 269 

Paying  for,  on  basis  of  fat^and 

calculated  casein 276 

Paying  for,  on  basis  of  "fat 

plus  2" 264 

Paying  for.  on  basis  of  weight  257 
Relation  ot  casein  and  albumin 

in 172 

Relation  of  fat  and  casein  in.  .  164 
Rich,  composition  of  cheese 

from 237 

Ripening  for  cheese-making. .  .  18 

Salts  of 150 

Skimmed,  cheese  from 250 

Skimmed,  composition  of  cheese 

from 233 

Skimming,  effect  on  composi- 
tion and  yield  of  cheese.  ...  234 

Tests  for  dirt  in 435 

Treatment  of,  after  milking. .  .  10 

Water  in 139 

Whey  and  cheese-solids  in. ...  201 


Milk-cans,  rusty,  effect  on  rennet 

action 309 

Milk-casein,  action  of  acids  on. .  .  143 

Action  of  alkalis  on 145 

Action  of  enzyms  on 147 

Action  of  heat  on 146 

Action  of  rennet  on 146 

Action  of  salts  on 146 

Composition  of 141 

Effect  of  drouth  on 163 

Effect  of  pasturage  on 163 

In  factory  milk 163 

Physical  condition  of 142 

Rule  for  calculating  amount  of  170 
Strength  of  rennet  in  coagulat- 
ing   302 

Variations 161 

Milk-fat 140 

And  breeds  of  cows 157 

And  lactation 158 

Effect  of  pasturage  on 160 

Functions  in  cheese 177 

In  factory  milk 159 

In  whey 190 

Losses  of,  in  cheese-making.  .  .  188 

Paying  for  milk  on  basis  of.  ...  258 

Relation  to  cheese  yield 204 

Variation  of 157 

Milks,  different,  effects  of  rennet 

on 311 

Milk-pails,  sanitary 10 

Milk-solids,  calculation  of 438 

Milk-sugar 148 

Functions  of,  in  cheese-making  182 

In  cheese,  changes  of 333 

In  cheese-ripening 357 

In  unripe  cheese 328 

Lactic  acid  from 149 

Milling  curd,  objects  of 35 

Moisture,  deficient,  in  curd,  effects 

of 45 

Effect  on  body  9f  cheese 47 

Effect  on  chemistry  of  cheese- 
ripening  340 

Effect  on  finish 47 

Effect  of,  on  flavor  of  cheese ...  48 
Effect   on    keeping    quality  of 

cheese 48 

Effect  9n  texture  of  cheese 47 

Excessive,  in  curd,  effects  of .  .  46 

How  much  cheese  should  have  382 

In  cheese,  affecting  quality. ...  381 
In  cheese,  effect  on  weight  lost 

in  ripening 323 

In  cheese-making,  control  of .  .  48 

In  curd  and  cheese,  effects  of .  .  45 
In  cheese,  effect  of  texture  on 

loss  of 324 

Of  air,  effect  on  weight  lost  in 

ripening 317 

Relation  of,  to  acidity  in  curd.  4) 


INDEX 


485 


Page 
Moisture,  variation  in  loss  with 

different  kinds  of  cheese.  ...    321 
Why    it     affects     ripening     of 

cheese 353 

Moldy  cheese,  cause,  etc 134 

Monrad  test  for  ripening  milk.  .21,  432 

Mottled  color 89,   129 

Natural  starter 18 

Neufchatel    cheese  from  pasteur- 
ized milk,  making  of 404 

Neutral  salts  in  cheese-ripening.    334 
Off  flavors  in  cheese,  cause,  rem- 
edy, etc 116 

Open  texture,  cause,  prevention.    123 

Overdry  body 88 

Package,  cheese 91 

Pale  color,  cause,  remedy,  etc.  .  .    129 
Paracasein,  action  of  calcium  salts 

on 304 

And  casein,  rela^n  of 305 

Change  of  casein  into 303 

Digestion  by  rennet 306 

Distinction  from  casein 303 

Precipitation  by  calcium  salts.    304 
Paraffin  coating  on  cheese,  effect 

on  quality 389 

Covering  cheese  with 74,  387 

Paraffining      cheese,      effect     on 

weight  lost  in  ripening 319 

Paranuclein  in  cheese 330 

Pasteurized  milk,  cheese  from ...      60 
Pasturage,  effect  on  casein  in  milk   163 

Pasty  body 87 

Patrons'  statement 451 

Paying  for  milk  at  cheese-factories  253 
On  basis  of  cheese   yield  and 

solids 261 

On  basis  of  fat 258 

On  basis  of  fat  and  calculated 

casein 276 

On  basis  of  fat  and  casein 269 

On  basis  of  "fat  plus  2"  method  264 

On  basis  of  weight 257 

Pepsin,     commercial,     action    in 

cheese-ripening 365 

Enzym 312 

Method  of  testing 434 

Use  in  cheese-making 64,  312 

Peptones  in  cheese 330 

Perfect  body 87 

Color 88 

Flavor 82 

Texture 85 

Picnic  cheese,  size  of 44 

Piling  of  curd 32 

Pin-hole  texture 86 

Plans  of  factory  construction.  ...    105 

Poison  in  cheese 68 

Porous  texture 86 

Pressing  curd 40 

At  high  temperatures,  effects  of     41 
At  low  temperatures,  effects  of     41 


Page 

Pressing  curd,  conditions  of 40 

How  regulated 42 

Objects  of 41 

Temperature  of  curd  at 40 

Print  cheese,  size  of 44 

Profits  from   proper  ripening  of 

cheese ; 39 1 

Propagation  of  starter 20 

Protein,  brine-soluble,  in  cheese- 
ripening 359 

Proteins,  changes  in  cheese-ripen- 
ing     330 

In  cheese,  agents  changing. ...    355 

In  unripe  cheese 328 

Qualities,  commercial,  of  cheese.  .      80 
Quality  of  cheese  and  composition  243 

Affected  by  moisture 381 

Effect  of  freezing  on 390 

Effect  of  paraffin  coating 389 

Effect  of  temperature  on 388 

Quevenne  lactometer,  use  of.  ...   438 

Quick  flavor 82 

Quick-ripening  cheese 60 

Rancid  flavor 83 

Records,   system   of,   for  cheese- 
making 16 

Red  spots  in  cheese 89 

Rennet  action  and  acidity 51 

Effect  of  acid  salts  on 308 

Effect  of  acids  on 306 

Effect  of  alkaline  salts  on .....   308 

Effect  of  alkalis  on 308 

Effect  of  borax  on 308 

Effect  of  calcium  salts  on 306 

Effect  of  chloroform  on 308 

Effect  of  formalin  on 308 

Effect  of  metals  on 309 

Effect  of  rusty  milk-cans  on ...    309 

Effect  of  salt  on 308 

Effect  of  temperature  on 309 

In  cheese-ripening 361 

On  calcium  salts  of  milk 304 

On  casein 146 

On  different  milks 311 

Rennet     coagulation,     effect     of 

water  on 307 

Explanation  of 302 

Imperfect,  causes  of 23 

Rennet,  effect  of  heat  on 310 

Effect  of  sunlight  on 310 

Effect  on  cheese-ripening 346 

Effect  on  freshly  drawn  milk.  .    310 

Source  of 300 

Strength  of,  in  coagulating  milk  302 

Test.  Marschall 430 

Test,  Monrad .' 432 

Rennet-enzym,  conditions  of 

action 306 

Dissolving  action  of 306 

Rennet-extract,    addition    of,  to 

milk 23 

Amount  to  use 22 


486        SCIENCE    AND    PRACTICE    OF    CHEESE-MAKING 


Rennet-extract,  commercial 301 

How  made 300 

Method  of  testing 433 

Rennin  of  rennet 299 

Rich  milk,  composition  of  cheese 

from 237 

Rinds,  cracked,  cause,  etc 133 

Ripe  milk,  acidity  of 21 

Ripeness  of  milk,  finding  degrees 

of 21 

Ripening  milk  for  cheese-making     18 

Milk,  objects  of 18 

Of  cheese 313 

Of  cheese,  acid  salts  in 334 

Of  cheese,  changes  in 314 

Of  cheese,  changes  in  proteins 

in 330 

Of  cheese,  chemical  changes  in  327 
Of  cheese,  effect  of  temperature 

on  weight  lost  in 315 

Of  cheese,  measuring  rate  of.  .   336 

Of  cheese,  neutral  salts  in 334 

Of  cheese,  profits  from  proper.  391 
Rule  for  calculating  casein  in  milk  1 70 
Rusty  milk-cans,  effect  on  rennet 

action 309 

Rusty  spots,  cause,  etc 131 

Sale  of  cheese 71 

Salt,  amount  to  use  on  curd 38 

Effect  on  cheese-ripening 343 

Effect  on  rennet  action 308 

How  to  apply  to  curd 39 

In  cheese 89 

In  cheese,  testing ,      90 

In  unripe  cheese 329 

When  to  put  on  curd 37 

Salting  curd,  effects  of 39 

Curd 37 

Salts,  acid,  in  unripe  cheese 328 

Action  of,  on  casein 146 

Neutral,  in  unripe  cheese 328 

Of  milk 150 

Of  milk,  functions  of,  in  cheese- 
making 184 

Salvy  body 87 

Sampling  cheese 80 

Sanitary  milking-pails 10 

Scale  of  points  for  judging 92 

Science  of  cheese-making 137 

Score-cards,  commercial 94 

Educational 94 

Scoring  cheese,  method  of 93 

Seamy  color 89,  130 

Septic-tank  drainage 100 

Shape  of  cheese,  effect  of  weight 

lost  in  ripening 320 

Shipment,  boxing  cheese  for.  ...      77 

Of  cheese 71 

Weighing  cheese  for 76 

Shipping  cheese 73 

Silky  body 87 

Site  of  factory 97 


Size  and  loss  of  weight 387 

Size  of  cheese,  effect  on  weight 

lost  in  ripening 320 

Skim-milk  cheese 250 

Skimming  milk,  effect  of,  on  com- 
position of  cheese 234 

Effect  on  yield  of  cheese 234 

Skimmed    milk,    composition    of 

cheese  from 233 

Slow-ripening  cheese 60 

Smooth  body 87 

Soaked-curd    process    of    cheese- 
making 57 

Solid  body 87 

Solids,  cheese-producing,  in    dif- 
ferent milks 200 

Solids,  not  fat  in  milk,  calculation 

of 439 

Sour  flavor 83 

Specks,  white,  in  cheese-ripening  332 

Square  cheese,  size  of 44 

Stable  flavor 83 

Standard      for     cheese,     United 

States 237 

Standards  of  states  for  cheese.  . .   241 

Starter,  commercial 19 

Effect  on  yield  of  cheese 69 

Natural 18 

Preparation  of 18 

Propagation  of 20 

Use  9f,  in  cheese-making 21 

Stenciling  cheese-boxes 77 

Stiff  body 87 

Stilton  cheese,  making  of 398 

Stinkers,  cause,  prevention 116 

Stirred-curd    process    of    cheese- 
making 55 

Stirring  curd  after  cutting 28 

Stirring  curd  to  dry  it 32 

Straight  color 88 

Streaked  color 89 

Stringing  of  curd  on  hot  iron,  31,  35,  37 
Strings   of    curd   on    hot-iron    in 

cheddaring 35 

Length  of,  at  salting 37 

Strong  flavor 82 

Sugar  in  cheese-ripening 357 

In  milk 148 

Milk,  in  unripe  cheese 328 

Sunlight,  effect  on  rennet 310 

Supplies  for  cheese-factory 106 

Sweet  flavor 83 

Swiss-hole  texture 86 

Tainted  flavor 83 

Tallowy  flavor 83 

Temperature  and  loss  of  weight  in 

cheese-ripening 315 

Effect  on  rennet  action 309 

Effect  of,  on  chemical  changes 

in    cheese-ripening 338 

Influence  on  loss  of  weight  in 
ripening 386 


INDEX  487 


Page 
Temperature  of  curd  at  pressing.      40 

Of  heating  curd 29 

Of  ripening,  effect  on  quality.  .    388 
Test  for  acidity  of  milk,  whey,  etc.  426 

For  casein 440 

For  dirt  in  milk 435 

Hot-iron 439 

For  acidity  for  ripening  milk.  .      21 

Testing  acidity  of  whey 429 

Body  of  cheese 87 

Cheese 80 

Cheese  for  salt 89 

Flavor  of  cheese 81 

Methods  of 423 

Pepsin,  method  of 434 

Rennet-extract,  method  of.  ...   433 
Texture,  cause,  etc.,  of  defects  in  121 

Close 86 

Defects   in,  cause,   prevention, 

etc 121 

Fish-eye,  cause,  prevention,  etc.  126 
Gassy,  cause,  prevention,  etc..  124 
Greasy,  cause,  prevention,  etc.  125 

Loose 86,  123 

Mechanical  holes 86 

Of  cheese  and  acidity 52 

Of  cheese,  definition  of 84 

Of  cheese,  effect  of  moisture  on  47 
Of  cheese,  effect  on  loss  of 

moisture   324 

Of  cheese,  testing : 84 

Of  curd  in  cheddaring 34 

Open,  cause,  prevention,  etc..  .    123 

Perfect 85 

Pin-hole 86 

Porous 86 

Swiss-hole 86 

Translucent  color 88 

Turning  cheese 72 

Twins,  cheddar,  size  of 40 

Unclean  surface,  cause,  etc 133 

Uncolored  cheese 89 

United  States  cheese  standard.  .  .    237 
Water,    calculating    cheese    yield 

for  different  percentages  of .  .    224 

Effect  on  rennet  action 307 

Functions  of,  in  cheese 180 

In  cheese,  value  to  consumers.  383 
In  cheese,  value  to  dairymen.  .  380 

In  milk 139 

Relation  of,  to  cheese  yield.  ...    198 

Water-supply  of  factory 99 

Watery  body 88 

Wav.  color 89 

Waxy  body 87 

WeaK  body 87 

Weedy  flavor 83 

Weighing  cheese  for  shipment.  .  .      76 
Weight,  loss  in  cheese-ripening.  .    314 


Page 
Weight,  lost  in  cheese-ripening, 

effect  of  moisture  of  air  on  317 
Lost  by  paraffined  cheese.  .319,  387 
Lost  in  ripening,  effect  of  mois- 
ture in  cheese  on 323 

Lost  in  ripening,  effect  of  size 

of  cheese  on 320,  387 

Lost  in  cheese-ripening,  effect 

of  temperature  on 315 

Lost  in  ripening  at  factories.  .  .  380 
Lost  in  ripening,   influence  of 

temperature  on 386 

Lost  in  ripening,  reduction  of.  383 

Paying  for  milk  by 257 

Whey,  acidity  of,  at  salting  curd  37 

Acidity  of,  in  heating  curd ....  30 
Acidity  of,    when    drawn   from 

curd 31 

And  cheese,  distribution  of  milk 

constituents  in 203 

Composition  of 195 

Distribution  and  value  of 66 

Expulsion  of,  and  acidity 52 

Fat  in 190 

Removal  of,  from  curd 31 

Testing  acidity  of 429 

Variations  of  constituents. ....  197 

When  to  remove  from  curd.  .  .  31 

Whey-butter,  manufacture  of .  .  .  65 

Whey-solids  in  different  milks.  .  .  201 

White  specks  in  cheese 88,  332 

Wisconsin  curd- test 435 

Yeasts 296 

Yeasty  cheese,  cause,  prevention, 

etc 126 

Yield    of     cheese,     accuracy    of 

methods  of  calculating 226 

Of  cheese  and  milk  constituents  186 
Of  cheese,  calculating  from  fat 

Of  cheese,  calculating  from  fat 

and  casein 216,  220 

Of  cheese,   effect  of  skimming 

milk  on 234 

Of  cheese,  effect  of  starters  on     69 

Of  cheese,  factors  of 186 

Of  cheese,  methods  of  calculat- 
ing     211 

Of  cheese,  relation  of  fat  and 

casein  to 187 

Of  cheese,  relation  of  milk-fat 

to..: 204 

Of  cheese,  relation  of  water  to  198 
Of  cheese  with   different   per- 
centages of  water,  calculation 

of 224 

Of  cottage-cheese 403 

Of  ripe  cheese,  calculation  of .  .    225 
Young  American  Cheddars,  size  of     44 


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Forage  Crops  Other  Than  Grasses 

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Soiling  Crops  and  the  Silo 

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The  Study  of  Breeds 

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Tomato  Culture 

By  WILL  W.  TRACY.  The  author  has  rounded  up  in  this 
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The  Potato 

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Illustrated.  200  pages.  5x7  inches.  Cloth $0.75 

Dwarf  Fruit  Trees 

By  F.  A.  WAUGH.  This  interesting  book  describes  in  detail 
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Farm  Grasses  of  the  United  States  of  America 

By  WILLIAM  JASPER  SPILLMAN.  A  practical  treatise  on 
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The  Book  of  Corn 

By  HERBERT  MYRICK,  assisted  by  A.  D.  SHAMEL,  E.  A. 
BURNETT,  ALBERT  W.  FULTON,  B.  W.  SNOW,  and  other  most 
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marketing  and  uses  of  maize  in  America  and  elsewhere,  for 
farmers,  dealers  and  others.  Illustrated.  372  pages.  5x7 
inches.  Cloth.  $1.50 

The    Hop  — Its    Culture  and  Care,  Marketing 
and  Manufacture 

By  HERBERT  MYRICK.  A  practical  handbook  on  the  most 
approved  methods  in  growing,  harvesting,  curing  and  selling 
hops,  and  on  the  use  and  manufacture  of  hops.  The  result  of 
years  of  research  and  observation,  it  is  a  volume  destined  to  be 
an  authority  on  this  crop  for  many  years  to  come.  It  takes  up 
every  detail  from  preparing  the  soil  and  laying  out  the  yard, 
to  curing  and  selling  the  crop.  Every  line  represents  the 
ripest  judgment  and  experience  of  experts.  Size,  5x8;  pages, 
300;  illustrations,  nearly  150;  bound  in  cloth  and  gold;  price, 
postpaid, $i.So 

Tobacco  Leaf 

By  J.  B.  KILLEBREW  and  HERBERT  MYKICK.  Its  Culture 
and  Cure,  Marketing  and  Manufacture.  A  practical  handbook 
on  the  most  approved  methods  in  growing,  harvesting,  curing, 
packing  and  selling  tobacco,  with  an  account  of  the  opera- 
tions in  every  department  of  tobacco  manufacture.  The 
contents  of  this  book  are  based  on  actual  experiments  in  field, 
curing  barn,  packing  house,  factory  and  laboratory.  It  is  the 
only  work  of  the  kind  in  existence,  and  is  destined  to  be  the 
standard  practical  and  scientific  authority  on  the  whole  sub- 
ject of  tobacco  for  many  years.  506  pages  and  150  original 
engravings.  5x7  inches.  Cloth $2.00 


Farmer's  Cyclopedia 
of  Agriculture 


A  Compendium  of  Agricultural  Science  and  Praftice 
on  Farm,  Orchard  and  Garden  Crops,  and  the 
Feeding  and  Diseases  of  Farm  Animals  •  :  •  : 

*By    EARLEY  VERNON  WILCOX,   Ph.D 
CLARENCE   BEAMAN  SMITH,    M.S 

Associate  Editors  in  the  Office  of  Experiment  Stations*  United  Slmtes 
Department  of  Agriculture 

TlHis  is  a  new,  practical,  and  complete  pres- 
I     entation  of  the  whole  subject  of  agricul- 
ture in  its  broadest  sense.    It  is  designed 
for  the  use    of  agriculturists  who   de- 
sire up-to-date,  reliable  information  on 
all   matters   pertaining  to   crops   and   stock,  but 
more   particularly  for  the   actual  farmer.      The 
volume  contains 

Detailed  directions  for  the  culture  of  every 
important  field,   orchard,   and   garden   crop 

grown  in  America,  together  with  descriptions  of 
their  chief  insect  pests  and  fungous  diseases,  and 
remedies  for  their  control.  It  contains  an  ac- 
count of  modern  methods  in  feeding  and  handling 
all  farm  stock,  including  poultry.  The  diseases 
which  affect  different  farm  animals  and  poultry 
are  described,  and  the  most  recent  remedies  sug- 
gested fdr  controlling  them. 

Every  bit  of  this  vast  mass  of  new  and  useful 
information  is  authoritative,  practical,  and  easily 
found,  and  no  effort  has  been  spared  to  include 
all  desirable  details.  There  are  between  6,000 
and  7,000  topics  covered  in  these  references,  and 
it  contains  700  royal  8vo  pages  and  nearly  500 
suberb  half-tone  and  other  original  illustrations, 
making  the  most  perfect  Cyclopedia  of  Agricul- 
ture ever  attempted. 

Handsomely  bound  in  cloth,  £J.5O;    half  morocco 
(t)*ry  jumpluouj  .  £4.5  O.  postpaid 


ORANGE  JUDD  COMPANY, 


THIS  BOOK  IS  DUE  ON  THE  LAST  DATE 
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THIS  BOOK  ON  THE  DATE  DUE.  THE  PENALTY 
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FEB    17  1934 

MAR  24  1934 

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UAK  21  1937 

Jt'N  30  1933 

rm 

T  '-    \R     T  r\  F"»  w 

- 

MAY  2  3  1960 

PHYSICS  LIBR 

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REC  0  LD    DEC  - 

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